TypeError: expected string or bytes-like object when installing pip packages

[JordanKadish]

Environment

• pip version: 20.2.4
• Python version: 3.9
• OS: Arch Linux

Description

When running any pip install command, I run into this error unless I run the install as super user
Expected behavior

the module installs
How to Reproduce

pip install <requests, pylint, etc>

Output

$ pip install requests
Defaulting to user installation because normal site-packages is not writeable
ERROR: Exception:
Traceback (most recent call last):
  File "/usr/lib/python3.9/site-packages/pip/_internal/cli/base_command.py", line 228, in _main
    status = self.run(options, args)
  File "/usr/lib/python3.9/site-packages/pip/_internal/cli/req_command.py", line 182, in wrapper
    return func(self, options, args)
  File "/usr/lib/python3.9/site-packages/pip/_internal/commands/install.py", line 323, in run
    requirement_set = resolver.resolve(
  File "/usr/lib/python3.9/site-packages/pip/_internal/resolution/legacy/resolver.py", line 183, in resolve
    discovered_reqs.extend(self._resolve_one(requirement_set, req))
  File "/usr/lib/python3.9/site-packages/pip/_internal/resolution/legacy/resolver.py", line 388, in _resolve_one
    abstract_dist = self._get_abstract_dist_for(req_to_install)
  File "/usr/lib/python3.9/site-packages/pip/_internal/resolution/legacy/resolver.py", line 331, in _get_abstract_dist_for
    skip_reason = self._check_skip_installed(req)
  File "/usr/lib/python3.9/site-packages/pip/_internal/resolution/legacy/resolver.py", line 236, in _check_skip_installed
    req_to_install.check_if_exists(self.use_user_site)
  File "/usr/lib/python3.9/site-packages/pip/_internal/req/req_install.py", line 438, in check_if_exists
    if not self.req.specifier.contains(existing_version, prereleases=True):
  File "/usr/lib/python3.9/site-packages/packaging/specifiers.py", line 790, in contains
    item = parse(item)
  File "/usr/lib/python3.9/site-packages/packaging/version.py", line 57, in parse
    return Version(version)
  File "/usr/lib/python3.9/site-packages/packaging/version.py", line 296, in __init__
    match = self._regex.search(version)
TypeError: expected string or bytes-like object

A solution I have seen posted online is to replace the regex search version line with self._regex.search(str(version))

[uranusjr]

See #9348. TL;DR This is an Arch issue (more specifically, Arch’s modification to their pip package).