Requirement already satisfied: pytz>=2015.7 in /home/docs/checkouts/readthedocs.org/user_builds/python-semver/envs/latest/lib/python3.7/site-packages (from babel!=2.0,>=1.3->sphinx->-r docs/requirements.txt (line 2)) (2020.1)
Collecting sphinxcontrib-htmlhelp
  Downloading sphinxcontrib_htmlhelp-1.0.3-py2.py3-none-any.whl (96 kB)
Collecting sphinxcontrib-applehelp
  Downloading sphinxcontrib_applehelp-1.0.2-py2.py3-none-any.whl (121 kB)
Collecting sphinxcontrib-jsmath
  Downloading sphinxcontrib_jsmath-1.0.1-py2.py3-none-any.whl (5.1 kB)
Collecting sphinxcontrib-devhelp
  Downloading sphinxcontrib_devhelp-1.0.2-py2.py3-none-any.whl (84 kB)
Collecting sphinxcontrib-qthelp
  Downloading sphinxcontrib_qthelp-1.0.3-py2.py3-none-any.whl (90 kB)
Building wheels for collected packages: sphinx-argparse
  Building wheel for sphinx-argparse (setup.py): started
  Building wheel for sphinx-argparse (setup.py): finished with status 'done'
  Created wheel for sphinx-argparse: filename=sphinx_argparse-0.2.5-py3-none-any.whl size=11549 sha256=a6cd6938c3c655193f230e0181f48d037539475be6989b7f17d59760167f5c54
  Stored in directory: /tmp/pip-ephem-wheel-cache-s8zdxc9_/wheels/4a/4c/12/83c88bdc1bc352d7036de2891b5d6729adcf1bda3bab015560
Successfully built sphinx-argparse
ERROR: Exception:
Traceback (most recent call last):
  File "/home/docs/checkouts/readthedocs.org/user_builds/python-semver/envs/latest/lib/python3.7/site-packages/pip/_internal/cli/base_command.py", line 228, in _main
    status = self.run(options, args)
  File "/home/docs/checkouts/readthedocs.org/user_builds/python-semver/envs/latest/lib/python3.7/site-packages/pip/_internal/cli/req_command.py", line 182, in wrapper
    return func(self, options, args)
  File "/home/docs/checkouts/readthedocs.org/user_builds/python-semver/envs/latest/lib/python3.7/site-packages/pip/_internal/commands/install.py", line 379, in run
    requirement_set
  File "/home/docs/checkouts/readthedocs.org/user_builds/python-semver/envs/latest/lib/python3.7/site-packages/pip/_internal/resolution/resolvelib/resolver.py", line 191, in get_installation_order
    weights = get_topological_weights(graph)
  File "/home/docs/checkouts/readthedocs.org/user_builds/python-semver/envs/latest/lib/python3.7/site-packages/pip/_internal/resolution/resolvelib/resolver.py", line 242, in get_topological_weights
    assert len(weights) == len(graph)
AssertionError