comparison mercurial/context.py @ 8527:f9a80054dd3c

use 'x is None' instead of 'x == None'

The built-in None object is a singleton and it is therefore safe to
compare memory addresses with is. It is also faster, how much depends
on the object being compared. For a simple type like str I get:

            | s = "foo" | s = None
  ----------+-----------+----------
  s == None | 0.25 usec | 0.21 usec
  s is None | 0.17 usec | 0.17 usec

8526:f78eadbb5769

        acache = {}

        # prime the ancestor cache for the working directory
        for c in (self, fc2):
            if c._filerev == None:
                pl = [(n.path(), n.filenode()) for n in c.parents()]
                acache[(c._path, None)] = pl

        flcache = {self._repopath:self._filelog, fc2._repopath:fc2._filelog}
        def parents(vertex):

8527:f9a80054dd3c

        acache = {}

        # prime the ancestor cache for the working directory
        for c in (self, fc2):
            if c._filerev is None:
                pl = [(n.path(), n.filenode()) for n in c.parents()]
                acache[(c._path, None)] = pl

        flcache = {self._repopath:self._filelog, fc2._repopath:fc2._filelog}
        def parents(vertex):