Cannot determine consistent method resolution order (MRO) for "OrderedSet" when used with Python 2.7

[gvanrossum]

I have installed those stubs for Python 2.7 and am manipulating mypy to find them, by running mypy as follows (~/v27 is a virtualenv):

mypy test.py --python-version 2.7 --python-executable~/v27/bin/python

This give me the error

/Users/guido/v27/lib/python2.7/site-packages/ordered_set-stubs/__init__.pyi:10: error: Cannot determine consistent method resolution order (MRO) for "OrderedSet"

When used with Python 3 all is well.

[rominf]

Thank you for bug report, @gvanrossum!

[gvanrossum]

Actually it looks like this was a bug in typeshed -- we're fixing it (though you'll have to wait for the next mypy release to get the fix). See python/typeshed#2602.