rebase: explicitly tests for None
Changeset
361bccce566a removed the mutable default value, but did not explicitly
tested for None. Such implicit checking can introduce semantic and performance
issue. We move to an explicit check for None as recommended by PEP8:
https://www.python.org/dev/peps/pep-0008/#programming-recommendations
localrepo: deprecated '_link'
That method had a total on 1 internal user...
G: changed mercurial/localrepo.py