False positive error?

I see error for code:
```
def func(choice: str, default: str='y') -> bool:
    values = ('yes', '') if default == 'y' else ('yes',) # error: Unsupported right operand type for in ("object")
    # values = ('yes', '') if True else ('yes',) # ok (!)
    return choice in values
```
Is it a bug? mypy version is `0.641`
