Draft: operations: Allow rebase to work if patch has already been applied

Recently it appears there has been an uptick of rebase failures due to "this patch has already been applied" errors. If a target branch contains changes that are already in the source branch, and a user rebases, this failure would cause the rebase to stop.

We now skip these empty commits and allow the rebase to continue. This is already with squash.

Relates to gitlab#351017 (closed)