I don't know why it doesn't work, but it avoids this fatal error on startup:
> hg debugshell Traceback (most recent call last): File "hg", line 58, in <module> File "mercurial\dispatch.pyc", line 143, in run File "mercurial\dispatch.pyc", line 232, in dispatch File "mercurial\dispatch.pyc", line 254, in _rundispatch File "mercurial\ui.pyc", line 316, in load File "mercurial\rcutil.pyc", line 98, in rccomponents File "mercurial\rcutil.pyc", line 68, in default_rc_resources File "mercurial\utils\resourceutil.pyc", line 102, in contents File "<frozen zipimport>", line 775, in contents AssertionError
I assume the py2 version of py2exe never hit this because importlib.resources
failed to import.