tests: test more cases where a file got replaced by a copy This adds a test where a file is modified on one branch and is renamed onto another file in another branch. That should ideally be automatically resolved (by propagating the modification to the rename destination). Alternatively, it could be considered a modify/delete conflict. It should at least not be automatically resolved by ignoring the modification. However, that is what actually happens with the changeset-centric algorithm since I broke it in b4057d001760 (merge: when rename was made on both sides, use ancestor as merge base, 2020-01-22). Before that commit, it resulted in a modify/delete conflict. The filelog-centric algorithm was broken already before that commit. Differential Revision: https://phab.mercurial-scm.org/D8652