pip error cannot import name md5

Traceback (most recent call last):
  File "/usr/local/bin/pip", line 11, in <module>
    load_entry_point('pip==19.1.1', 'console_scripts', 'pip')()
  File "/usr/local/lib/python2.7/site-packages/pkg_resources/__init__.py", line 489, in load_entry_point
    return get_distribution(dist).load_entry_point(group, name)
  File "/usr/local/lib/python2.7/site-packages/pkg_resources/__init__.py", line 2843, in load_entry_point
    return ep.load()
  File "/usr/local/lib/python2.7/site-packages/pkg_resources/__init__.py", line 2434, in load
    return self.resolve()
  File "/usr/local/lib/python2.7/site-packages/pkg_resources/__init__.py", line 2440, in resolve
    module = __import__(self.module_name, fromlist=['__name__'], level=0)
  File "/usr/local/lib/python2.7/site-packages/pip/_internal/__init__.py", line 19, in <module>
    from pip._vendor.urllib3.exceptions import DependencyWarning
  File "/usr/local/lib/python2.7/site-packages/pip/_vendor/urllib3/__init__.py", line 8, in <module>
    from .connectionpool import (
  File "/usr/local/lib/python2.7/site-packages/pip/_vendor/urllib3/connectionpool.py", line 29, in <module>
    from .connection import (
  File "/usr/local/lib/python2.7/site-packages/pip/_vendor/urllib3/connection.py", line 38, in <module>
    from .util.ssl_ import (
  File "/usr/local/lib/python2.7/site-packages/pip/_vendor/urllib3/util/__init__.py", line 6, in <module>
    from .ssl_ import (
  File "/usr/local/lib/python2.7/site-packages/pip/_vendor/urllib3/util/ssl_.py", line 8, in <module>
    from hashlib import md5, sha1, sha256
ImportError: cannot import name md5

I was just having this problem. This fixed it for me:

https://stackoverflow.com/questions/59269208/errorrootcode-for-hash-md5-was-not-found-when-using-any-hg-mercurial-command