I think this is a bug, actually. It's going to be an incompatibility in `ast.parse` so we'll probably want to only enable it in Python 3.8.

This should have stringified annotations:

>>> p = ast.parse("""
... from __future__ import annotations
... a: 1
... """)
>>> p.body[1].annotation  # ACTUAL
<_ast.Num object at 0x1048cf470>

>>> p.body[1].annotation  # EXPECTED
<_ast.Str object at 0x1048cf6a0>