The commit 87d1809657 changed the time when
digests are sent by 3 hours to account for moving from the US East Coast to the
West Coast, but didn't change the time period exception in the
`check-rabbitmq-queue` script.
Closes#5415
Structurally, this queue has the same property as the missed_message
one, namely that it accumulates things and processes them only every
few minutes.
This should stop Zulip from paging in response to slow queries
accumulating when a server restart happens.
This causes `upgrade-zulip-from-git`, as well as a no-option run of
`tools/build-release-tarball`, to produce a Zulip install running
Python 3, rather than Python 2. In particular this means that the
virtualenv we create, in which all application code runs, is Python 3.
One shebang line, on `zulip-ec2-configure-interfaces`, explicitly
keeps Python 2, and at least one external ops script, `wal-e`, also
still runs on Python 2. See discussion on the respective previous
commits that made those explicit. There may also be some other
third-party scripts we use, outside of this source tree and running
outside our virtualenv, that still run on Python 2.