Use a condition variable (threading.Event) rather than sleeps and checking a

Use a condition variable (threading.Event) rather than sleeps and checking a
global to determine when the server is ready to be used.  This slows the test
down, but should make it correct.  There was a race condition before where the
server could have assigned a port, yet it wasn't ready to serve requests.  If
the client sent a request before the server was completely ready, it would get
an exception.  There was machinery to try to handle this condition.  All of
that should be unnecessary and removed if this change works.  A NOTE was
added as a comment about what needs to be fixed.

The buildbots will tell us if there are more errors or
if this test is now stable.