Shallow copy of user handlers leads to a nil map assignment when
enabling pprof. Since the map is being modified, it should probably
be deep copied into the server context, which fixes the crash.
When using the embed functionality, you can't call the Server.Stop()
function until StartEtcd returns, which can block until there is a call
to Server.Stop() in error situations. Since we have a catch-22, the
ReadyNotify() can be called manually by the user if they wish to wait
for the server startup, or in parallel with a timeout if they wish to
cancel it after some time.
Chzz pointed out that this is also more consistent with the
etcdserver.Start() behaviour too.
purpleidea pointed out that this is actually more correct too, because
we can now register the stop interrupt handler before we block on
startup.
Anthony Romano