[SAC] trac database backups

[Sandro Santilli]

As I prepare to make a full hotcopy backup of all trac instances
in order to upgrade Trac to 1.2, I found what look like being
old backups under the trac environments directories, like these:

  ubuntugis/db/postgres.21.1429742384.bak.gz
  ubuntugis/db/postgres.29.1462395524.bak.gz

Those two (but there are similar in all other envs) are from
April 2015 and May 2016, do you know what/who created them and
why ?

I'm assuming actual backups live elsewhere (different machine)
but can anyone confirm that ?

--strk;