Tox: Add debug test output
Tox: Set environment variables properly
Make the database backend retry operations on ResourceClosedError and StaleDataError too. Make the operations close the connection if failure occurs (can't retry on broken connection). Fixes #1786.
Don't close the session. Just rollback and/or close.
Close the sessions before disposing the engines as the engines won't close connections held up in sessions.
Use a session manager that has different behavior before the fork (effectivelly hardcodes NullPool - everything else is unreliable).
Update changelog.
Merge pull request #1899 from celery/more-reliable-sqlalchemy

Make the database backend more reliable
Cosmetics for #1736
flakes
Stress test app now loads on Windows
Sets release date for 3.1.10
Fix issue with timer starting after stop() is called. Now it doesn't start in this situation.
Match the signature used in the rest of the code.
Result cache populated by join_native even if cache disabled
Stresstests: Delete results after bigtasksbigvalue test
Task: Do not send error emails for expected errors (@task(throws=...))
Removes duplicate _set_cache.  Closes #1940
Stresstests: Backend may not implement .forget
Master branch is now 3.2a1