[ovs-dev] [PATCHv2] tests: Fix race condition waiting for monitor thread.

[YAMAMOTO Takashi]

> Occasionally, test #770 "ofproto-dpif - ofproto-dpif-monitor 1" would
> fail, because the testsuite looked in the logs for evidence of a thread
> being created, but it checked before vswitchd was able to spawn the
> thread.
> 
> This patch fixes the race by modifying the commands that check for
> creation/termination of threads to wait until they see the messages
> instead.
> 
> Signed-off-by: Joe Stringer <joestringer at nicira.com>

Reviewed-by: YAMAMOTO Takashi <yamamoto at valinux.co.jp>