iotests: fix 194: filter out racy postcopy-active event

The event is racy: it will not appear in the output if bitmap is
migrated during downtime period of migration and postcopy phase is not
started.

Fixes: ae00aa2 "iotests: 194: test also migration of dirty bitmap"
Reported-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-Id: <20230607143606.1557395-1-vsementsov@yandex-team.ru>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

tests/qemu-iotests/194

@@ -74,6 +74,11 @@ with iotests.FilePath('source.img') as source_img_path, \
 
     while True:
         event1 = source_vm.event_wait('MIGRATION')
+        if event1['data']['status'] == 'postcopy-active':
+            # This event is racy, it depends do we really do postcopy or bitmap
+            # was migrated during downtime (and no data to migrate in postcopy
+            # phase). So, don't log it.
+            continue
         iotests.log(event1, filters=[iotests.filter_qmp_event])
         if event1['data']['status'] in ('completed', 'failed'):
             iotests.log('Gracefully ending the `drive-mirror` job on source...')

tests/qemu-iotests/194.out

@@ -14,7 +14,6 @@ Starting migration...
 {"return": {}}
 {"data": {"status": "setup"}, "event": "MIGRATION", "timestamp": {"microseconds": "USECS", "seconds": "SECS"}}
 {"data": {"status": "active"}, "event": "MIGRATION", "timestamp": {"microseconds": "USECS", "seconds": "SECS"}}
-{"data": {"status": "postcopy-active"}, "event": "MIGRATION", "timestamp": {"microseconds": "USECS", "seconds": "SECS"}}
 {"data": {"status": "completed"}, "event": "MIGRATION", "timestamp": {"microseconds": "USECS", "seconds": "SECS"}}
 Gracefully ending the `drive-mirror` job on source...
 {"return": {}}