No branch push system note for branch rewinds

Summary

When a branch is force pushed to remove commits from the head of the previous branch, no "Added 3 commits" style note is added to the MR note stream.

Steps to reproduce

Open an MR with a branch with at least 2 commits. Force push the HEAD~ commit to the same branch on the remote.

Expected behavior

A note mentioning that the branch was changed (Removed 1 commit?).

Actual behavior

No system note.