merge with stable

match: make exactmatcher.visitchildrenset return file children as well Previously, if we had an exactmatcher like ['foo.txt', 'a/bar.txt', 'a/b/c/baz.txt'], we'd get back the following data: '.': {'a'} 'a': {'b'} 'a/b': {'c'} 'a/b/c': 'this' 'a/b/c/d': set() This was incorrect, since visitchildrenset explicitly says not to pay attention to 'foo.txt' and 'a/bar.txt' by not returning them or 'this'. Given the near impossibility of making visitchildrenset reliabbly produce only subdirectories, a previous commit has made it documented and expected that visitchildrenset can return a set containing both files and subdirectories to visit, instead of implying/requiring that visitchildrenset() return 'this' if there are files to visit. This makes the code for exactmatcher match this clarified documentation. Differential Revision: https://phab.mercurial-scm.org/D4365

match: document that visitchildrenset might return files At least when using includematcher, and probably most matchers, we do not know if a/b/f refers to a file 'f' in a/b, or a subdirectory 'f' in a/b, so most matchers will return {'f'} for visitchildrenset('a/b'). Arguably, all matchers could/should - for exactmatcher, we know that 'f' is a file, but there's no reason to return 'this' for visitchildrenset('a/b') causing code to investigate 'a/b/x', for example. Differential Revision: https://phab.mercurial-scm.org/D4364