When using Branches: and PR is merged, rebase detection can fail and cause pr to be re-created

[jerry-skydio]

Upload change from branch A but target other branch B with Branches:. When change merges and you fetch B again, revup continues to upload the PR to B, does the cherry-pick, finds that it succeeds and produces an empty commit, then finds the patch-id of the empty commit, compares against original, and mistakenly finds that it changed and thus re-uploads.

[jerry-skydio]

this seems to only happen for relative chains that get targeted to a different branch. possibly only when the relative change forces a push of the parent