diffstat: be more picky when marking file as 'binary' (issue2816) The 'Bin' marker was added to every changed file for which we could not find any diff changes. This included binary files but also copy/renames and mode changes. Since Mercurial regular diff format emits a 'Binary file XXX has changed' line when fed with binary files, we use that and the usual git marker to tell them from other cases. In particular, new empty files are no longer reported as binary. Still, this fix is not complete since copy/renames/mode changes are now reported as '0' lines changes, instead of 'Bin'.