iotests: Fix another race in 030

We can't rely on a non-paused job to be present and running for us.
Assume that if the job is not present that it completed already.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

tests/qemu-iotests/030

@@ -547,11 +547,14 @@ class TestEIO(TestErrors):
         while not completed:
             for event in self.vm.get_qmp_events(wait=True):
                 if event['event'] == 'BLOCK_JOB_ERROR':
+                    error = True
                     self.assert_qmp(event, 'data/device', 'drive0')
                     self.assert_qmp(event, 'data/operation', 'read')
                     result = self.vm.qmp('query-block-jobs')
+                    if result == {'return': []}:
+                        # Job finished too quickly
+                        continue
                     self.assert_qmp(result, 'return[0]/paused', False)
-                    error = True
                 elif event['event'] == 'BLOCK_JOB_COMPLETED':
                     self.assertTrue(error, 'job completed unexpectedly')
                     self.assert_qmp(event, 'data/type', 'stream')