Presumably autoland. Where does that live? Would be good to just say in the error message.
smacleod says, "if you run into a commit on autoland, it went through MozReview - rather than rebase onto autoland itself, rebase onto the review request from the review repo (the pull command will be on the review request). Then when you repush to review and attempt to land it will not conflict". The failure message should include something like this.
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