The name is ambiguous, but the image_id is not!  This fixes problems
during upgrade where upgrade thinks the container is upgraded (due to
an incorrect digest) when in fact it is not.
Fixes: 0826c45e0cb5d60fcf8cd71cd14edd34a6997cd4
Signed-off-by: Sage Weil <sage@newdream.net>
                                 out, err, code = call(
                                     ctx,
                                     [
-                                        container_path, 'image', 'inspect', image_name,
+                                        container_path, 'image', 'inspect', image_id,
                                         '--format', '{{.RepoDigests}}',
                                     ],
                                     verbosity=CallVerbosity.DEBUG)