> pg_stop_backup() doesn't complete until all the WAL segments needed to
> restore from the backup are archived. If archive_command is failing,
> that never happens.
OK, so we need a way out of that cycle if the user is issuing
pg_stop_backup because they *already know* that archive_command is
failing. Right now, there's no way out other than a fast shutdown,
which is a bit user-hostile.
--Josh Berkus