In test_replication_servers_working, we delete a bunch of directories
without deleting hashes.pkl, then verify that nothing at that level is a
directory.
This would be trivially true except that throughout the test, we have
the replicators running constantly. However, we never verified that the
replicators actually *have* run and had a chance to re-create the
missing directories.
Now, stop the replicators before doing the deletes, run them
synchronously between doing the deletes and verifying that there are no
directories, and start them again before the final set of assertions.
Change-Id: I841f8250eb7abfb0fcdfca5c106f65e6e94dce0c
61c9aa4bf3