The claim in the comment from c8ec3dfcf6, that we can and should use
the current deploy's venv, misses one key case -- when upgrading the
operating system, the current deploy's venv is unworkable, since it
was configured for a previous version of Python. As such, any attempt
to load Django to verify the version of PostgreSQL it is talking to
must happen after the venv is configured.
Move the database version check into
`scripts/lib/check-database-compatibility`, which also moves it after
the new venv is configured.
Because we no longer reliably know, at `apt-get upgrade` time, what
version of PostgreSQL is installed, we hold all versions of the
pgroonga packages.
Alex Vandiver
Anders Kaseorg