identify: simplify the dirty check This is equivalent to the previous code, but it seems better to be explicit about what aspects of dirty are being ignored. Perhaps they shouldn't be, since the help text says 'followed by a "+" if the working directory has uncommitted changes'. Both merges and branch changes are committable, even if the files are unchanged. Additionally, this will make the `identify` command notice missing subrepo files, once subrepos are taught to look for missing files.

tests: tweak the subrepo dirty state tests This is a continuation of 439b4d005b4a. I overlooked that blackbox logs also have a dirty marker. Also, the `hg update --check` test was updating to a revision where the deleted file wasn't tracked, which is why status seemed to show the deleted file was restored.

match: combine regex code for path: and relpath: The regexes for path: and relpath: patterns are the same (since the paths have already been normalized at the point we create the regexes). I don't think the "if pat == '.'" will have any effect relpath: because relpath: patterns will have the root directory already normalized to '' by pathutil.canonpath() (unlike path:, for which the root gets normalized to '.' by util.normpath()).

match: remove unnecessary '^' from regexes The regexes are passed to re.match(), which matches against the beginning of the input, so the '^' doesn't do anything. Note that unrooted patterns, such as globs and regexes from .hgignore are instead achieved by adding '.*' to the expression given by the user. (That's unless the user's expression started with '^', in which case the '.*' is not added, perhaps to keep the regex cleaner?)

sparse: access status fields by name instead of deconstructing it The status tuples has had named fields for a few years now.

sparse: move printing of sparse config changes function into core As part of the port, all arguments now have default values of 0. Strings are now also given the i18n treatment.

sparse: move code for clearing rules to core This is a pretty straightforward port.

sparse: move post commit actions into core Instead of wrapping committablectx.markcommitted(), we inline the call into workingctx.markcommitted(). Per smf's review, workingctx is the proper location for this code, as committablectx is the shared base class for it and memctx. Since this code touches the working directory, it belongs in workingctx.

cleanupnode: do not use generator for node mapping The 'successors' part of the mappings used of be a tuple. This avoid issue from code consuming the generator "by mistake". For example, an extension inspecting the mapping content used to be able to iterate over the successors mapping without consequence. Since the mapping are small we do not expect any performance impact we use tuple again for this.

histedit: use scmutil.cleanupnodes (BC) This is marked as BC because the strip backup file name has changed.