BUG: type aliasing is not allowed to be compared using isinstance()
- [X] closes #21078
- [ ] tests added / passed
- [X] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

As raised in #21078, Python 3.5.4 supports the using `isinstance()` with `typing.re.Pattern` But it does not support the same method in 3.5.2.

``` Python
Python 3.5.2 (default, Nov 23 2017, 16:37:01)
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import re
>>> import typing
>>> isinstance(re.compile(''), typing.re.Pattern)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.5/typing.py", line 260, in __instancecheck__
    raise TypeError("Type aliases cannot be used with isinstance().")
TypeError: Type aliases cannot be used with isinstance().
```

This Bugfix PR is to revert the `re_type` to be back to what it used to be before the update with the new release.
