Comment 1 for bug 1775491

yes, it is easily reproducible on local env by increasing the nova's config option metadata_cache_expiration value to something higher (i did 50 sec).

It fail in both place in verify_empty_devices()[1] as well as in verify_device_metadata()[2]

[1] https://github.com/openstack/tempest/blob/5aeb551a58078abd34884583ac70ad425f4590ba/tempest/api/compute/servers/test_device_tagging.py#L310

[2] https://github.com/openstack/tempest/blob/5aeb551a58078abd34884583ac70ad425f4590ba/tempest/api/compute/servers/test_device_tagging.py#L306

as matt mentioned in gerrit, we should go with wait loop here than hard coded sleep.