fsmonitor: use modern match API It seems like fsmonitor/__init__.py was based on a pretty old version of dirstate.py. Let's copy over the changes from the following two commits: 55c449345b10 (match: add isexact() method to hide internals, 2014-10-29) 3c346969c321 (dirstate: avoid match.files() in walk(), 2015-05-19)