copies: extract function for deciding whether to use changeset-centric algos We'll eventually have a "experimental.copies.read-from=changeset-only" option too and I don't want to spread the logic for determining if we should use changeset-centric of filelog-centric algorithms. Differential Revision: https://phab.mercurial-scm.org/D6163

getrenamedfn: get copy data from context object if configured The function returned from getrenamedfn() calls filelog.renamed(). That won't work when storing copy metadata in the changeset. I've just switched to a simple implementation here. We may or may not need to optimize it later, possibly by optimizing the callers. No more tests fail with "--extra-config-opt experimental.copies.read-from=compatibility)" than they did before this patch. Differential Revision: https://phab.mercurial-scm.org/D6162

branchmap: implement __contains__() We have good occurences of `if branch in branchmap()` in our code. If __contains__() is not implemented then it will use __iter__() to find whether the element exists or not which is not good. I am bit confused that whether I should move existing callers to hasbranch() or this patch is a good way. Differential Revision: https://phab.mercurial-scm.org/D6206

branchmap: prevent using __getitem__() in branchheads() branchheads() can directly use self._entries instead. Differential Revision: https://phab.mercurial-scm.org/D6205

branchmap: dynamically resolve type of branchcache class This is required to support subclassing. Thanks to Yuya for suggesting this in D6151. Differential Revision: https://phab.mercurial-scm.org/D6204

copies: print list of divergent renames in sorted order The current order is not obvious to the user (and I may change it in a later patch). Lexicographical order seems like the obvious choice here. Differential Revision: https://phab.mercurial-scm.org/D6227