transactions that aren't retried don't rollback

[daniel-sanche]

in Transaction.call, rollback is called when retries are exhausted, or when pre-commit fails, but other exceptions cause an immediate raise, without any rollback.

To fix this, the entire __call__ function should be wrapped in a try...except block, that causes a rollback before any exceptions are raised out of the transaction

[kolea2]

It looks like this was fixed in #767, closing. @daniel-sanche please reopen if needed. Thanks!