Guardian adds functionality on top of Django auth system to set
per object permissions. Its problem is that it is has poor performance.
So we decided to remove it in release 1.4.0, but we still kept the
option to revert back to an older version which used Guardian.
See commit 49799440a4 for more details.
This commit is the final piece in the string of commits which move
us towards completely removing guardian from our codebase. The way
we do it as follows:
If you are upgrading from a version <= 1.3.10, you first need to
upgrade to 1.4.x (we recommend 1.4.2). The reason is that we
deprecated Guardian in this version. Once you have upgraded to
1.4.x we can be sure that your Zulip installation doesn't depend
on Guardian and all the data has been successfully migrated away from
Guardian. The second step is to upgrade to latest release which will
not include any reference to Guardian in the codebase. After this
commit migrating directly to the latest release will not work because
in that case Guardian data will not migrate.
The backward incompatible change that this introduces is that
we have squashed all the migrations till version 1.4.0. This was
necessary to remove Guardian because it was needed by the reverse
migration. These migrations were from 0001 to 0028.
Fixes#5420
a66b7b7083