rollback: avoid unsafe rollback when not at tip (issue2998) You can get into trouble if you commit, update back to an older changeset, and then rollback. The update removes your valuable changes from the working dir, then rollback removes them history. Oops: you've just irretrievably lost data running nothing but core Mercurial commands. (More subtly: rollback from a shared clone that was already at an older changeset -- no update required, just rollback from the wrong directory.) The fix assumes that only "commit" transactions have irreplaceable data, and allows rolling back non-commit transactions as always. But when rolling back a commit, check that the working dir is checked out to tip, i.e. the changeset we're about to destroy. If not, abort. You can get back the old (dangerous) behaviour with --force.