Upgrade: 2.3-2.4-supplmental.sh can result in Pg deadlocks

[Galen Charlton]

The parallel create index concurrently statements executed by 2.3-2.4-supplemental.sh can occasionally deadlock, due to two different issues. One of them is a PostgreSQL bug fixed by the following commit, but not released as of this writing.

http://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=c3d09b3

The other was attempts by the script to create multiple indexes on acq.edi_messages and action.hold_request in parallel.

Evergreen 2.4.0

[Galen Charlton (gmc)]

A fix is available at the tip of the user/gmcharlt/avoid-deadlock-during-supplemental-upgrade branch in the working/Evergreen repository:

http://git.evergreen-ils.org/?p=working/Evergreen.git;a=shortlog;h=refs/heads/user/gmcharlt/avoid-deadlock-during-supplemental-upgrade

[Galen Charlton (gmc)]

Note for anybody who was very quick on the draw -- I've force-pushed a corrected patch.

[Dan Scott (denials)]

The fix worked well for us for upgrading a copy of our production database; I've pushed this to master and rel_2_4. Thanks Galen!