This commit adds a management command that will run regularly
as a cron job to send zulip updates to realms based on their
current and latest zulip_update_announcements_level.
For realms with:
* level = None: Send a group DM to admins notifying them about
this new feature & suggestion to set the stream accordingly.
* level = 0:
* If stream is still not configured, wait for a week
before setting their level to latest level. They will
miss updates until their configure the stream.
* If stream is configured, send updates.
* level > 0: Send one message/update per level & increase
the level by 1 till the latest level.
Fixes#28604.
This is a prep commit to extract out the logic to
create message from 'internal_send_huddle_message'
into a separate function 'internal_prep_huddle_message'.
We will use this new function to get the huddle message
without sending it immediately.
In general, we never want to use savepoints.
This prep commit adds savepoint=False in do_send_messages
as we don't want to just rollback to this savepoint and
proceed if we encounter any error while sending zulip updates
via cron.
A user who was no longer subscribed to a private stream kept their
UserMessage row for a message sent while they were in it; this is
expected. However, they _also_ kept that row even if the message was
moved to a different private stream that they were also not subscribed
to. This violates the invariant that users without subscriptions
never have UserMessage rows.
This `if new_stream is not None` block was improperly indented,
causing it to only run if the propagation mode was not `change_one`.
Since the block controlled creation and deletion of UserMessage rows,
this led to messages being improperly still visible to members of the
old stream if they were being moved from public to private streams.
Clients also failed to receive `delete_message` events, so the
messages remained visible in their feeds until they reloaded the
application.
Only affects zulipchat, by being based on the BILLING_ENABLED setting.
The restricted backends in this commit are
- AzureAD - restricted to Standard plan
- SAML - restricted to Plus plan, although it was already practically
restricted due to requiring server-side configuration to be done by us
This restriction is placed upon **enabling** a backend - so
organizations that already have a backend enabled, will continue to be
able to use it. This allows us to make exceptions and enable a backend
for an org manually via the shell, and to grandfather organizations into
keeping the backend they have been relying on.
This commit adds a realm-level setting named
'zulip_update_announcements_stream' that configures the
stream to which zulip updates should be posted.
Fixes part of #28604.
This commit renames the realm-level setting
'signup_notifications_stream' to 'signup_announcements_stream'.
The new name reflects better what the setting does.
This commit renames the realm-level setting 'notifications_stream'
to 'new_stream_announcements_stream'.
The new name reflects better what the setting does.
Previously, in DM disabled org messaging to bot was not working when
starting new conversation and adding bot as recipient because of not
updating on recipient change. And secondly, self messaging was not
allowed.
This commit ensures that the DM to bot and self are allowed irrespective
of dm restrictions.
tests: Verify DMs adhere to DM restriction policy.
Fixes#28412
Signed-off-by: sayyedarib <sayyedaribhussain4321@gmail.com>
Rather than pass around a list of message objects in-memory, we
instead keep the same constructed QuerySet which includes the later
propagated messages (if any), and use that same query to pick out
affected Attachment objects, rather than limiting to the set of ids.
This is not necessarily a win -- the list of message-ids *may* be very
long, and thus the query may be more concise, easier to send to
PostgreSQL, and faster for PostgreSQL to parse. However, the list of
ids is almost certainly better-indexed.
After processing the move, the QuerySet must be re-defined as a search
of ids (and possibly a very long list of such), since there is no
other way which is guaranteed to correctly single out the moved
messages. At this point, it is mostly equivalent to the list of
Message objects, and certainly takes no less memory.
This applies access restrictions in SQL, so that individual messages
do not need to be walked one-by-one. It only functions for stream
messages.
Use of this method significantly speeds up checks if we moved "all
visible messages" in a topic, since we no longer need to walk every
remaining message in the old topic to determine that at least one was
visible to the user. Similarly, it significantly speeds up merging
into existing topics, since it no longer must walk every message in
the new topic to determine if the user could see at least one.
Finally, it unlocks the ability to bulk-update only messages the user
has access to, in a single query (see subsequent commit).
This is a preparatory commit that refactors the check_update_message
method to extract the checks containing whether a user can edit the
message or not into a separate method -validate_message_content_edit,
so that it can be re used later.
This logic was apparently missed when we implemented private streams
with shared history; the correct check is to look at whether the user
can access message history in the stream, which used to be equivalent
to whether it's a private stream.
This commit removes the stale 'email_gateway' parameter
from 'do_send_messages' function.
This should have been removed in 6c473ed75f,
when the call to 'build_message_send_dict' was removed
from 'do_send_messages'.
The endpoint was lacking validation that the authentication_methods dict
submitted by the user made sense. So e.g. it allowed submitting a
nonsense key like NoSuchBackend or modifying the realm's configured
authentication methods for a backend that's not enabled on the server,
which should not be allowed.
Both were ultimately harmless, because:
1. Submitting NoSuchBackend would luckily just trigger a KeyError inside
the transaction.atomic() block in do_set_realm_authentication_methods
so it would actually roll back the database changes it was trying to
make. So this couldn't actually create some weird
RealmAuthenticationMethod entries.
2. Silently enabling or disabling e.g. GitHub for a realm when GitHub
isn't enabled on the server doesn't really change anything. And this
action is only available to the realm's admins to begin with, so
there's no attack vector here.
test_supported_backends_only_updated wasn't actually testing anything,
because the state it was asserting:
```
self.assertFalse(github_auth_enabled(realm))
self.assertTrue(dev_auth_enabled(realm))
self.assertFalse(password_auth_enabled(realm))
```
matched the desired state submitted to the API...
```
result = self.client_patch(
"/json/realm",
{
"authentication_methods": orjson.dumps(
{"Email": False, "Dev": True, "GitHub": False}
).decode()
},
)
```
so we just replace it with a new test that tests the param validation.
This leads to significant speedups. In a test, with 100 random unique
event classes, the old code processed a batch of 100 rows (on average
66-ish unique in the batch) in 0.45 seconds. Doing this in a single
query processes the same batch in 0.0076 seconds.
This is preparatory work towards adding a Topic model.
We plan to use the local variable name as 'topic' for
the Topic model objects.
Currently, we use *topic as the local variable name for
topic names.
We rename local variables of the form *topic to *topic_name
so that we don't need to think about type collisions in
individual code paths where we might want to talk about both
Topic objects and strings for the topic name.
Rename and restructure these comparison variables such that we don't
have a possibly impossible case for presence.last_connected_time being
None.
Fixes#25498.
We previously used get_accessible_user_ids to check whether the
sender can access all DM recipients, which was not efficient as
it queries the Message table. This commit updates the code to
make sure we use get_inaccessible_user_ids which is much more
efficient as it limits the queries to only DM recipients and
also queries the Message table only if needed.
This can still be optimized further as mentioned in #27835 but
this commit is a nice first step.
This fixes a bug introduced in
6f93ab72c0 where deactivating a realm
would fail with an exception that sessions cannot be cleared inside
database transactions.
Actions that change the number of user counts adds a deferred_work
queue processor job immediately update the billing service about your
change.
This helps to avoid having users see stale state for how many
users they have when trying to pay.
This is a rename of the previous
enqueue_register_realm_with_push_bouncer_if_needed but is clearer
about the fact that this will also upload audit logs if available.
This is the only operating editing audit logs not already using a
transaction, and having it do so will simplify an upcoming interface
to be able to assume it is always inside a transaction.
This commit adds code to not include original details of senders like
name, email and avatar url in the message objects sent through events
and in the response of endpoint used to fetch messages.
This is the last major commit for the project to add support for
limiting guest access to an entire organization.
Fixes#10970.
Earlier, the event sent when an onboarding step (hotspot till now)
is marked as read generated an event with type='hotspots' and
'hotspots' named array in it.
This commit renames the type to 'onboarding_steps' and the array
to 'onboarding_steps' to reflect the fact that it'll also contain
data for elements other than hotspots.
This commit adds a new endpoint 'users/me/onboarding_steps'
deprecating the older 'users/me/hotspots' to mark hotspot as read.
We also renamed the view `mark_hotspot_as_read` to
`mark_onboarding_step_as_read`.
Reason: Our plan is to make this endpoint flexible to support
other types of UI elements not just restricted to hotspots.
Adds a helper since there are only a few different parameters for
all BillingSession child clases, `build_support_url`.
Also, renames `get_support_url` to more explicitly note that it
is for realms: `get_realm_support_url`.
This commit adds code to not allow Zulip Cloud organizations that are not
on the Plus plan to change the "can_access_all_users_group" setting.
Fixes#27877.
This commit moves the 'update_license_ledger_if_needed' and its
helper function 'update_license_ledger_for_automanaged_plan'
to the 'BillingSession' abstract class.
This refactoring will help in minimizing duplicate code while
supporting both realm and remote_server customers.
We want to both (a) take a lock on the UserProfile row, and (b)
modify the passed-in UserProfile object, so that callers see the
changes in the object they hold. Unfortunately,
`select_for_update` cannot be combined with `refresh_from_db`
(https://code.djangoproject.com/ticket/28344). Call
`select_for_update` and throw away the result, so that we know we have
the lock on the row, then re-fill the `user_profile` object with the
values now that the lock exists.
This commit updates get_fake_email_domain to accept realm.host as
argument instead of the Realm object since we only use realm.host
to get the fake email domain.
This is a preparatory commit for the limited guest feature as we
would be sending the fake email of the message sender in message
event object to a guest user who cannot access the sender and
there we would need to compute the fake email.
Now, the topic wildcard mention follows the following
rules:
* If the topic has less than 15 participants , anyone
can use @ topic mentions.
* For more than 15, the org setting 'wildcard_mention_policy'
determines who can use @ topic mentions.
Earlier, topic wildcard mentions followed the same restriction
as stream wildcard mentions, which was incorrect.
Fixes part of #27700.
This commit moves a major portion of the 'update_plan`
view to a new shared 'BillingSession.do_update_plan' method.
This refactoring will help in minimizing duplicate code
while supporting both realm and remote_server customers.
Guests might lose access to deactivated users if the user
is not involved in any DM with guest. This commit adds
code to send "realm_user/remove" events for such cases.
We now send user creation events to recipient users
when sending DMs if recipients gain access to either
sender or other pariticpating users in the DM.
This commit adds code to send "realm_user/remove" event
when a guest user loses access to a user due to the user
being unsubscribed from one or more streams.
This commit adds code to send user creation events to
guests who gain access to new subscribers and to the
new guest subscribers who gain access to existing
stream subscribers.
The presence and user status update events are only sent to accessible
users, i.e. guests do not receive presence and user status updates for
users they cannot access.
This commit adds code to make sure that update events for changing
a user's role, email, etc. are not sent to guests who cannot access
the modified user.
We do not send the original user data in user creation events
to guests if user access is restricted in realm, as they would
receive the information about user if user is subscribed to some
common streams after account creation.
This commit adds code to send stream deletion events when
unsubscribing non-admin users from private streams and
when unsubscribing guests from public streams since
non-admins cannot access unsubscribed private streams
and guests cannot access unsubscribed public streams.
It was discovered by the Zulip development team that active users who
had previously been subscribed to a stream incorrectly continued being
able to use the Zulip API to access metadata for that stream. As a
result, users who had been removed from a stream, but still had an
account in the organization, could still view metadata for that
stream (including the stream name, description, settings, and an email
address used to send emails into the stream via the incoming email
integration). This potentially allowed users to see changes to a
stream’s metadata after they had lost access to the stream.
This bug was present in all Zulip releases prior to today's Zulip
Server 7.5.
This commit removes "email_address" field from Subscription objects
and we would instead a new endpoint in next commit to get email
address for stream with proper access check.
This change also fixes the bug where we would include email address
for the unsubscribed private stream as well when user did not have
permission to send message to the stream, and having email allowed
the unsubscribed user to send message to the stream.
Note that the unsubscribed user can still send message to the stream
if the user had noted down the email before being unsubscribed
and the stream token is not changed after unsubscribing the user.
This commit adds code to unset is_web_public and is_realm_public fields
on attachments when deactivating a stream as we do not want to allow
spectators to access them after the stream is deactivated.
This commit also adds a comment explaining why we don't use
do_change_stream_permission to set the privacy fields on deactivating
a stream.
Fixes#27634.
We did not unset is_realm_public field on attachements when unarchiving
streams, but we do unset is_web_public field. This commit adds code to
unset the is_realm_public field as well as we make the stream private
while unarchiving it.
Rename the existing 'wildcard_mentioned' flag to
'stream_wildcard_mentioned'.
The 'wildcard_mentioned' flag is deprecated and exists for
backwards compatibility.
We have two separate flags for stream and topic wildcard mentions,
i.e., 'stream_wildcard_mentioned' and 'topic_wildcard_mentioned',
respectively.
* stream wildcard mentions: `@all`, `@everyone`, and `@stream`
* topic wildcard mentions: `@topic`
The `wildcard_mentioned` flag is included in the events and
API response if either `stream_wildcard_mentioned` or
`topic_wildcard_mentioned` is set.
The event for stream typing notifications is no longer sent
to the long_term_idle subscribers of the stream.
This helps to reduce the tornado's work of parsing super-long
JSON-encoded lists of user IDs in large streams. Now the lists
are shorter.
Earlier, the 'wildcard_mentioned' flag was set for both the
stream and topic wildcard mentions.
Now, the 'topic_wildcard_mentioned' flag is set for topic
wildcard mentions, and the 'wildcard_mentioned' flag is set for
stream wildcard mentions.
We will rename the 'wildcard_mentioned' flag to
'stream_wildcard_mentioned' in a later commit.
We now send "realm_user/update" (and "realm_bot/update" for bots)
events with "is_active" field when deactivating and reactivating
users, including bots.
We would want to use "remove" event for a user losing access
to another user for #10970, so it is better to use "update"
event for deactivation as we only update "is_active" field
in the user objects and the clients still have the data for
deactivated users.
Previously, we used to send "add" event for reactivation along
with complete user objects, but clients should have the data
for deactivated users as well, so an "update" event is enough
like we do when deactivating users.
This commit moves constants for system group names to a new
"SystemGroups" class so that we can use these group names
in multiple classes in models.py without worrying about the
order of defining them.
This commit renames permissions_configuration variable to
permission_configuration since the object contains config for
a single permission setting and thus permission_configuration
seems like a better name.
Previous behavior-
- Guest did not receive stream creation events for new
web-public streams.
- Guest did not receive peer_add and peer_remove events
for web-public and subscribed public streams.
This commit fixes the behavior to be -
- Guests now receive stream creation events for new
web-public streams.
- Guest now receive peer_add and peer_remove events for
web-public and subscribed public streams.
This commit updates code in bulk_remove_subscriptions and
bulk_add_subscriptions to return early if there are no
subscribers to remove or add to the streams.
This change helps us in avoiding unnecessary queries like the
one used to get subscribers list of streams, which is then used
to send events but we would not send any events if no subscribers
are added or removed and some more similar queries.
In this commit, we add a new dropdown 'Organization language' on
the `/new` and `/realm/register` pages. This dropdown allows setting
the language of the organization during its creation. This allows
messages from Welcome Bot and introductory messages in streams to be
internationalized.
Fixes a part of #25729.
Add an optional `automatic_new_visibility_policy` enum field
in the success response to indicate the new visibility policy
value due to the `automatically_follow_topics_policy` and
`automatically_unmute_topics_in_muted_streams_policy` user settings
during the send message action.
Only present if there is a change in the visibility policy.
This is a prep commit that extracts the following two methods
from '/actions/scheduled_messages' to reuse in the next commit.
* extract_stream_id
* extract_direct_message_recipient_ids
The 'to' parameter for 'POST /typing' will follow the same pattern
in the next commit as we currently have for the 'to' parameter in
'POST /scheduled_messages', so we can reuse these functions.
This commit replaces the value `private` with `direct` in the
`message_type` field for the `typing` events sent when a user
starts or stops typing a message.
This commit includes the message's sender id in the
'topic_participant_user_ids' set.
The 'participants_for_topic' function doesn't include the sender_id,
if the user is sending their first message in the topic, because
'participants_for_topic' queries the 'Message' table, but the message
is actually sent at a later stage in the codepath, resulting in
missing the sender_id in this case.
This is needed to set the 'wildcard_mentioned' flag for the sender's
user message in the case of topic wildcard mentions.
This doesn't lead to sending email and push notifications to the
sender because we have a check to skip notifications if the user
to receive notifications is the sender itself.
This should have been included in c0c30bc.
This commit adds two user settings, named
* `automatically_follow_topics_policy`
* `automatically_unmute_topics_in_muted_streams_policy`
The settings control the user's preference on which topics they
will automatically 'follow' or 'unmute in muted streams'.
The policies offer four options:
1. Topics I participate in
2. Topics I send a message to
3. Topics I start
4. Never (default)
There is no support for configuring the settings through the UI yet.
This fixes a regression introduced in
9954db4b59, where the realm's default
language would be ignored for users created via API/LDAP/SAML,
resulting in all such users having English as their default language.
The API/LDAP/SAML account creation code paths don't have a request,
and thus cannot pull default language from the user's browser.
We have the `realm.default_language` field intended for this use case,
but it was not being passed through the system.
Rather than pass `realm.default_language` through from each caller, we
make the low-level user creation code set this field, as that seems
more robust to the creation of future callers.
Adds support for bulk-adjusting a single user's membership in multiple
user groups in a single transaction in the low-level actions
functions, for future use by work on #9957.
This adds support for syncing user role via the newly added "role"
attribute, which can be set to either of
['owner', 'administrator', 'moderator', 'member', 'guest'].
Removes durable=True from the atomic decorator of do_change_user_role,
as django-scim2 runs PATCH operations in an atomic block.
Matching the topic exactly, as opposed to case-insensitively, is not a
common operation, and one that we want to make difficult to do
accidentally. Inline the single use case of it.
_default_manager is the same as objects on most of our models. But
when a model class is stored in a variable, the type system doesn’t
know which model the variable is referring to, so it can’t know that
objects even exists (Django doesn’t add it if the user added a custom
manager of a different name). django-stubs used to incorrectly assume
it exists unconditionally, but it no longer does.
Signed-off-by: Anders Kaseorg <anders@zulip.com>
Earlier whenever a new invitation is created a event was sent
to only admin users. So, if invites by a non-admins user are changed
the invite panel does not live update.
This commit makes changes to also send event to non-admin
user if invites by them are changed.
This commit does the backend changes required for adding a realm
setting based on groups permission model and does the API changes
required for the new setting `Who can create multiuse invite link`.
Creates process for demo organization owners to add an email address
and password to their account.
Uses the same flow as changing an email (via user settings) at the
beginning, but then sends a different email template to the user
for the email confirmation process.
We also encourage users to set their full name field in the modal for
adding an email in a demo organization. We disable the submit button
on the form if either input is empty, email or full name.
When the user clicks the 'confirm and set password' button in the
email sent to confirm the email address sent via the form, their
email is updated via confirm_email_change, but the user is redirected
to the reset password page for their account (instead of the page for
confirming an email change has happened).
Once the user successfully sets a password, then they will be
prompted to log in with their newly configured email and password.
To make creation of demo organizations feel lightweight for users,
we do not want to require an email address at sign-up. Instead an
empty string will used for the new realm owner's email. Currently
implements that for new demo organizations in the development
environment.
Because the user's email address does not exist, we don't enqueue
any of the welcome emails upon account/realm creation, and we
don't create/send new login emails.
This is a part of #19523.
Co-authored by: Tim Abbott <tabbott@zulip.com>
Co-authored by: Lauryn Menard <lauryn@zulip.com>
We now send stream creation and stream deletion events on
changing a user's role because a user can gain or lose
access to some streams on changing their role.
Users who used to be subscribed to a private stream and have been
removed from it since retain the ability to edit messages/topics, and
delete messages that they used to have access to, if other relevant
organization permissions allow these actions. For example, a user may be
able to edit or delete their old messages they posted in such a private
stream. An administrator will be able to delete old messages (that they
had access to) from the private stream.
We fix this by fixing the logic in has_message_access (which lies at the
core of our message access checks - access_message() and
bulk_access_messages())
to not rely on only a UserMessage row for checking access but also
verify stream type and subscription status.
**Background**
User groups are expected to comply with the DAG constraint for the
many-to-many inter-group membership. The check for this constraint has
to be performed recursively so that we can find all direct and indirect
subgroups of the user group to be added.
This kind of check is vulnerable to phantom reads which is possible at
the default read committed isolation level because we cannot guarantee
that the check is still valid when we are adding the subgroups to the
user group.
**Solution**
To avoid having another transaction concurrently update one of the
to-be-subgroup after the recursive check is done, and before the subgroup
is added, we use SELECT FOR UPDATE to lock the user group rows.
The lock needs to be acquired before a group membership change is about
to occur before any check has been conducted.
Suppose that we are adding subgroup B to supergroup A, the locking protocol
is specified as follows:
1. Acquire a lock for B and all its direct and indirect subgroups.
2. Acquire a lock for A.
For the removal of user groups, we acquire a lock for the user group to
be removed with all its direct and indirect subgroups. This is the special
case A=B, which is still complaint with the protocol.
**Error handling**
We currently rely on Postgres' deadlock detection to abort transactions
and show an error for the users. In the future, we might need some
recovery mechanism or at least better error handling.
**Notes**
An important note is that we need to reuse the recursive CTE query that
finds the direct and indirect subgroups when applying the lock on the
rows. And the lock needs to be acquired the same way for the addition and
removal of direct subgroups.
User membership change (as opposed to user group membership) is not
affected. Read-only queries aren't either. The locks only protect
critical regions where the user group dependency graph might violate
the DAG constraint, where users are not participating.
**Testing**
We implement a transaction test case targeting some typical scenarios
when an internal server error is expected to happen (this means that the
user group view makes the correct decision to abort the transaction when
something goes wrong with locks).
To achieve this, we add a development view intended only for unit tests.
It has a global BARRIER that can be shared across threads, so that we
can synchronize them to consistently reproduce certain potential race
conditions prevented by the database locks.
The transaction test case lanuches pairs of threads initiating possibly
conflicting requests at the same time. The tests are set up such that exactly N
of them are expected to succeed with a certain error message (while we don't
know each one).
**Security notes**
get_recursive_subgroups_for_groups will no longer fetch user groups from
other realms. As a result, trying to add/remove a subgroup from another
realm results in a UserGroup not found error response.
We also implement subgroup-specific checks in has_user_group_access to
keep permission managing in a single place. Do note that the API
currently don't have a way to violate that check because we are only
checking the realm ID now.
We want to make the callers be more explicit about the use of the
user group being accessed, so that the later implemented database lock
can be benefited from the visibility.
We do not want to access realm from "sender" field so that
we do not need to pass "sender__realm" argument to
select_related call when querying messages. We can instead
pass realm as argument to wildcard_mention_allowed.
We can directly get the realm object from Message object now
and there is no need to get the realm object from "sender"
field of Message object.
After this change, we would not need to fetch "sender__realm"
field using "select_related" and instead only passing "realm"
to select_related when querying Message objects would be enough.
This commit also updates a couple of cases to directly access
realm ID from message object and not message.sender. Although
we have fetched sender object already, so accessing realm_id
from message directly or from message.sender should not matter,
but we can be consistent to directly get realm from Message
object whenever possible.
We set stream_weekly_traffic field to "null" for Subscription
objects in zephyr mirror realm as we do not need stream traffic
data in zephyr mirror realm. This makes the subscription data
consistent with steams data.
This commit also udpates test to check never_subscribed data for
zephyr mirror realm.
Instead of having a "realm.is_zephyr_mirror_realm" check for every
get_streams_traffic call, this commit udpates get_streams_traffic to
accept realm as parameter and return "None" for zephyr mirror realm.
This migration applies under the assumption that extra_data_json has
been populated for all existing and coming audit log entries.
- This removes the manual conversions back and forth for extra_data
throughout the codebase including the orjson.loads(), orjson.dumps(),
and str() calls.
- The custom handler used for converting Decimal is removed since
DjangoJSONEncoder handles that for extra_data.
- We remove None-checks for extra_data because it is now no longer
nullable.
- Meanwhile, we want the bouncer to support processing RealmAuditLog entries for
remote servers before and after the JSONField migration on extra_data.
- Since now extra_data should always be a dict for the newer remote
server, which is now migrated, the test cases are updated to create
RealmAuditLog objects by passing a dict for extra_data before
sending over the analytics data. Note that while JSONField allows for
non-dict values, a proper remote server always passes a dict for
extra_data.
- We still test out the legacy extra_data format because not all
remote servers have migrated to use JSONField extra_data.
This verifies that support for extra_data being a string or None has not
been dropped.
Co-authored-by: Siddharth Asthana <siddharthasthana31@gmail.com>
Signed-off-by: Zixuan James Li <p359101898@gmail.com>
This commit removes the private stream suscriptions of the bot if the
original owner is deactivated and we change the owner to the user who
is reactivating the bot. We unsusbcribe the bot from private streams
that the new owner is not subscribed to.
Fixes part of #21700.
We remove bot's subscriptions for private streams to which the
new owner is not subscribed and keep the ones to which the new
owner is subscribed on changing owner.
This commit also changes the code for sending subscription
remove events to use transaction.on_commit since we call
the function inside a transactopn in do_change_bot_owner and
this also requires some changes in tests in test_events.
Earlier, for topic wildcard mentions, the 'wildcard_mentioned'
flag was set for all the user-messages. (similar to stream wildcard
mention).
The flag should be set for the topic participants only.
The bug was introduced in 4c9d26c.