The cancel_and_wait() function has been duplicated in 030 and 041. Move
it into iotests.py and let it return the event so tests can perform
additional asserts.
Note that 041's cancel_and_wait(wait_ready=True) is replaced by
wait_ready_and_cancel(), which uses the new wait_ready() and
cancel_and_wait() underneath.
Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>