commit: change default `editor` parameter to None

Flagged by PyCharm as a boolean not being callable later where it is used.
There's no actual bug here because of `if editor` checks before using.

Differential Revision: https://phab.mercurial-scm.org/D7768

mercurial/context.py

@@ -2738,7 +2738,7 b' class memctx(committablectx):'
         date=None,
         extra=None,
         branch=None,
-        editor=False,
+        editor=None,
     ):
         super(memctx, self).__init__(
             repo, text, user, date, extra, branch=branch
@@ -2899,7 +2899,7 b' class metadataonlyctx(committablectx):'
         user=None,
         date=None,
         extra=None,
-        editor=False,
+        editor=None,
     ):
         if text is None:
             text = originalctx.description()

mercurial/localrepo.py

@@ -2845,7 +2845,7 b' class localrepository(object):'
         date=None,
         match=None,
         force=False,
-        editor=False,
+        editor=None,
         extra=None,
     ):
         """Add a new revision to current repository.