pytype: stop excluding upgrade.py
The sole failure here was this, which is fixed by simply creating a set like the
caller, instead of a dict:
File "/mnt/c/Users/Matt/hg/mercurial/upgrade.py", line 73, in upgraderepo:
No attribute 'discard' on Dict[nothing, nothing] [attribute-error]
In Union[Any, Dict[nothing, nothing]]
Differential Revision: https://phab.mercurial-scm.org/D11911
#require docutils gettext
$ $TESTDIR/check-gendoc da
checking for parse errors