lfs: add a fileset for detecting lfs files This currently has the same limitation as {lfs_files}, namely it doesn't report removed files. We may want a dedicated 'lfs()' revset for efficiency, but combining this with the 'contains()' revset should be equivalent for now. Combining with 'set:added()' or 'set:modified()' inside 'files()' should be equivalent to a hypothetical lfs_adds() and lfs_modifies(). I wonder if there's a way to tweak the filesets to evaluate lazily, to close the efficiency gap. It would also be interesting to come up with a template filter for '{files}' that looked at the pattern to 'files()', and filtered appropriately. While passing a fileset as the pattern to `hg log` does filter '{files}', the set is evaluated against the working directory, so there's no way to list all non-lfs files above a certain size in all revisions, for example.

tests: stabilize ssh tests on Windows This seems like a somewhat common type of failure (double vs single quote), so I'm interested in ideas about how to avoid this. I doubt that we should automatically fall back from single quote to double quote, like with '/' vs '\'.

wireprotoserver: rename abstractserverproto and improve docstring The docstring isn't completely accurate for the current state of the world. But it does describe the direction future patches will be taking things. Differential Revision: https://phab.mercurial-scm.org/D2065