waitstone may report stone ready during restart after crash
When the stone is restarted following a crash, it performs recovery from
tranlogs. During this period, waitstone may incorrectly report that the
stone is ready for logins.
This is most dangerous in the presence of bug #41462, in which logins are
allowed during recovery; any commits during the recovery process can permanently
corrupt the repository.
Do not use waitstone as a test for login. Waiting until startstone returns
is a safe test that the stone is ready for login. startstone will not return
to the prompt until recovery is complete.