[PATCH] iotests.py: Wait for postmigrate in wait_migration

[Max Reitz <mreitz@redhat.com>]

Without this patch, I see intermittent failures in the new iotest 280
under high system load.  I have not yet seen such failures with other
iotests that use VM.wait_migration() and query-status afterwards, but
maybe they just occur even more rarely.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 tests/qemu-iotests/iotests.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tests/qemu-iotests/iotests.py b/tests/qemu-iotests/iotests.py
index 13fd8b5cd2..4da25c88f5 100644
--- a/tests/qemu-iotests/iotests.py
+++ b/tests/qemu-iotests/iotests.py
@@ -674,6 +674,9 @@ class VM(qtest.QEMUQtestMachine):
             log(event, filters=[filter_qmp_event])
             if event['data']['status'] == 'completed':
                 break
+        # The event may occur in finish-migrate, so wait for postmigrate
+        while self.qmp('query-status')['return']['status'] != 'postmigrate':
+            pass
 
     def node_info(self, node_name):
         nodes = self.qmp('query-named-block-nodes')
-- 
2.23.0