[leapp] leapp fails with error fails with pkg_resources.DistributionNotFound: urllib3>=1.21.1,!=1.25.0,!=1.25.1,<1.26

Issue

• Using leapp to upgrade system from Red Hat Enterprise Linux 7 to 8 fails with below traceback error:

#  leapp preupgrade
Traceback (most recent call last):
  File "/usr/bin/leapp", line 5, in <module>
    from pkg_resources import load_entry_point
  File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 3251, in <module>
    @_call_aside
  File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 3235, in _call_aside
    f(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 3264, in _initialize_master_working_set
    working_set = WorkingSet._build_master()
  File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 585, in _build_master
    return cls._build_from_requirements(__requires__)
  File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 598, in _build_from_requirements
    dists = ws.resolve(reqs, Environment())
  File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 786, in resolve
    raise DistributionNotFound(req, requirers)