While I was working on making 'future annotations' default, I noticed that dataclasses acts differently under the annotation feature. One example would be the file [signature.py]:

[ without future import]
 $ python t.py
X(a: int, b: int)
[ with future import]
 $ python t.py
X(a: '_type_a', b: '_type_b') -> '_return_type'

This is causing too much test to fail,
AssertionError: '_return_type' is not None

- C(x:'_type_x')->'_return_type'
+ C(x:collections.deque)

- C(x:'_type_x'=<factory>)->'_return_type'
+ C(x:collections.deque=<factory>)

- C(x:'_type_x')->'_return_type'
+ C(x:List[int])

(and more)