test_commit_diff: make sure we recorded a rename and not a copy

It was recorded as "copy" instead of "rename" as we didn't pass the
'bar' to wrapper.commit()

It didn't have any impact on response because response attrs won't
really have any difference b/w rename and copy. But this change is
to make sure that we have correct repo setup as explained by comments.
4 jobs for !41 with topic/default/commitDelta in 1 minute and 40 seconds (queued for 1 second)
latest merge request