Make test_copy_image_revert_lifecycle handle 409 on import retry

This test is very racy in general, and specifically on the post-revert
retry to do the import, it may start the next import before the previous
one has finished reverting. This patch makes it retry a few times with
delay if an HTTP 409 is received so it is tolerant of that situation once
it becomes possible in the subsequent patch to add import locking.

Change-Id: Ic933f170d43b290fd819e8527ecb60be7f7f3f89

glance/tests/functional/v2/test_images.py

@@ -17,6 +17,7 @@ import hashlib
 import os
 import subprocess
 import tempfile
+import time
 import uuid
 
 from oslo_serialization import jsonutils
@@ -5709,7 +5710,17 @@ class TestImagesMultipleBackend(functional.MultipleBackendFunctionalTest):
             {'method': {'name': 'copy-image'},
              'stores': ['file2', 'file3'],
              'all_stores_must_succeed': False})
-        response = requests.post(path, headers=headers, data=data)
+
+        for i in range(0, 5):
+            response = requests.post(path, headers=headers, data=data)
+            if response.status_code != http.CONFLICT:
+                break
+            # We might race with the revert of the previous task and do not
+            # really have a good way to make sure that it's done. In order
+            # to make sure we tolerate the 409 possibility when import
+            # locking is added, gracefully wait a few times before failing.
+            time.sleep(1)
+
         self.assertEqual(http.ACCEPTED, response.status_code)
 
         # Verify image is copied