DOC: Unable to import pandas on python 3.5.2
#### Code Sample, a copy-pastable example if possible

```python
import pandas
```
#### Problem description

Although it seems like a typing issue pandas is still affected, error:
```
root@ae9a5374fe6d:/buildbot# python -c "import pandas"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/local/lib/python3.5/dist-packages/pandas/__init__.py", line 55, in <module>
    from pandas.core.api import (
  File "/usr/local/lib/python3.5/dist-packages/pandas/core/api.py", line 5, in <module>
    from pandas.core.arrays.integer import (
  File "/usr/local/lib/python3.5/dist-packages/pandas/core/arrays/__init__.py", line 1, in <module>
    from .array_ import array  # noqa: F401
  File "/usr/local/lib/python3.5/dist-packages/pandas/core/arrays/array_.py", line 7, in <module>
    from pandas.core.dtypes.common import (
  File "/usr/local/lib/python3.5/dist-packages/pandas/core/dtypes/common.py", line 11, in <module>
    from pandas.core.dtypes.dtypes import (
  File "/usr/local/lib/python3.5/dist-packages/pandas/core/dtypes/dtypes.py", line 53, in <module>
    class Registry:
  File "/usr/local/lib/python3.5/dist-packages/pandas/core/dtypes/dtypes.py", line 84, in Registry
    self, dtype: Union[Type[ExtensionDtype], str]
  File "/usr/lib/python3.5/typing.py", line 552, in __getitem__
    dict(self.__dict__), parameters, _root=True)
  File "/usr/lib/python3.5/typing.py", line 512, in __new__
    for t2 in all_params - {t1} if not isinstance(t2, TypeVar)):
  File "/usr/lib/python3.5/typing.py", line 512, in <genexpr>
    for t2 in all_params - {t1} if not isinstance(t2, TypeVar)):
  File "/usr/lib/python3.5/typing.py", line 1077, in __subclasscheck__
    if super().__subclasscheck__(cls):
  File "/usr/lib/python3.5/abc.py", line 225, in __subclasscheck__
    for scls in cls.__subclasses__():
TypeError: descriptor '__subclasses__' of 'type' object needs an argument
```

To reproduce:
```
$ docker pull ursalab/amd64-ubuntu-16.04-python-3:worker
$ docker run -it ursalab/amd64-ubuntu-16.04-python-3:worker bash
# python -c "import pandas"
```

#### Output of ``pip freeze | grep pandas``

```
pandas==0.25.0
```
