Comment 3 for bug 1815153

I made this change to try and test scenario #4 but the test still passed which was unexpected:

diff --git a/nova/tests/functional/test_servers.py b/nova/tests/functional/test_servers.py
index 67c0fe9..c73d6a2 100644
--- a/nova/tests/functional/test_servers.py
+++ b/nova/tests/functional/test_servers.py
@@ -1409,6 +1409,19 @@ class ServerRebuildTestCase(integrated_helpers._IntegratedTestBase,
         allocs = allocs[rp_uuid]['resources']
         assertFlavorMatchesAllocation(flavor, allocs)

+ # Now let's hack the RequestSpec.is_bfv field to mimic migrating an
+ # old instance created before RequestSpec.is_bfv was set in the API,
+ # move the instance and verify that the RequestSpec.is_bfv is set
+ # and the instance still reports the same DISK_GB allocations as during
+ # the initial create.
+ ctxt = context.get_admin_context()
+ reqspec = objects.RequestSpec.get_by_instance_uuid(ctxt, server['id'])
+ del reqspec.is_bfv
+ reqspec.save()
+ reqspec = objects.RequestSpec.get_by_instance_uuid(ctxt, server['id'])
+ # Make sure it's not set.
+ self.assertNotIn('is_bfv', reqspec)
+
         rebuild_image_ref = (
             nova.tests.unit.image.fake.AUTO_DISK_CONFIG_ENABLED_IMAGE_UUID)
         # Now rebuild the server with a different image.
osboxes@osboxes:~/git/nova$

{0} nova.tests.functional.test_servers.ServerRebuildTestCase.test_rebuild_with_new_image [8.071310s] ... ok