Comment 4 for bug 1315668

Sounds like it could be a concurrency issue with mysqldb and sqlalchemy:

https://groups.google.com/forum/#!topic/sqlalchemy/wVyUoXorFrE

And here is a thread on using with_lockmode('update') with mysql and sqlalchemy and that's what the quotas query is doing:

https://groups.google.com/forum/#!topic/sqlalchemy/MBRcTJzi8Kk

http://stackoverflow.com/questions/14375666/sqlalchemy-prevent-automatic-closing

Might need to see which version of sqlalchemy we're running with in the gate and see if there are any newer versions with bug fixes for the mysqldb engine.