Perform finalizing transactional vote in PostReceivePack
In case git-receive-pack(1) doesn't perform any reference updates because of whatever reason we are left with no transactional votes. This is countered in SSHReceivePack by doing another finalizing vote, but don't in the smarthttp's PostReceivePack RPC. The result is that we may sometimes create replication jobs even though nothing has changed because Praefect didn't observe any votes.
We should fix this issue in PostReceivePack to use the same strategy as in SSHReceivePack.