backout: disable --merge with --no-commit (issue4874) Because "backout --merge" have to make a commit before merging, it doesn't work with --no-commit. We could change "backout --merge" to make a merge commit automatically, and --no-commit to bypass a merge commit, but that change would be undesirable because: a) it's hard to fix bad merges in general b) two commits would be created with the same --message So, this patch simply disables "--merge --no-commit".