Bug 1193137: Remove commit_manually decorator from app version update task.

[kmaglione]

As far as I can tell, what's happening on production is that, because we have a transaction.atomic block inside of a transaction.commit_manually block in the update_addon_appsupport cron job, we always end that block with a pending commit.

When that happens, in our version of django, anyway, the connection also seems to sometimes keep the in_atomic_block flag, which leaves that worker broken for any task that runs next.

I've confirmed that this change fixes at least the first part of the problem. That cron job no longer ends with a transaction error. I haven't been able to reproduce the TransactionManagementError: An error occurred in the current transaction. You can't execute queries until the end of the 'atomic' block. error in a local web instance yet, but I think this should fix that as well.

[kmaglione]

I tried to add a test for this. Unfortunately, the transaction management wrappers of the test harness mean that we never actually commit any transactions, and the exit transaction code that throws this error is never called. I can't think of a good way around this.

[magopian]

r+

[magopian]

I'm going to merge so the QA team has enough time to validate that before the micro-push