pip list --outdated and --uptodate broken

[alex-d-boyd]

Environment

• pip version:

C:\WINDOWS\system32>pip --version
pip 19.2 from c:\program files\python37\lib\site-packages\pip (python 3.7)

• Python version:

Python 3.7.4 (tags/v3.7.4:e09359112e, Jul  8 2019, 20:34:20) [MSC v.1916 64 bit (AMD64)] on win32

• OS:

C:\WINDOWS\system32>ver
Microsoft Windows [Version 10.0.18362.239]

Description
Running pip list with either --outdated or --uptodate switches generates a NoneType attribute error.
pip list with no switches, and pip list --not-required both function as expected. I have not tested other list switches.

Expected behavior
Expected a list of either outdated or up-to-date installed packages

How to Reproduce
Run either of the following commands:

• pip list --outdated
• pip list --uptodate

Output

C:\WINDOWS\system32>pip list --outdated
ERROR: Exception:
Traceback (most recent call last):
  File "c:\program files\python37\lib\site-packages\pip\_internal\cli\base_command.py", line 188, in main
    status = self.run(options, args)
  File "c:\program files\python37\lib\site-packages\pip\_internal\commands\list.py", line 156, in run
    packages = self.get_outdated(packages, options)
  File "c:\program files\python37\lib\site-packages\pip\_internal\commands\list.py", line 164, in get_outdated
    dist for dist in self.iter_packages_latest_infos(packages, options)
  File "c:\program files\python37\lib\site-packages\pip\_internal\commands\list.py", line 164, in <listcomp>
    dist for dist in self.iter_packages_latest_infos(packages, options)
  File "c:\program files\python37\lib\site-packages\pip\_internal\commands\list.py", line 195, in iter_packages_latest_infos
    best_candidate = evaluator.get_best_candidate(all_candidates)
  File "c:\program files\python37\lib\site-packages\pip\_internal\index.py", line 729, in get_best_candidate
    best_candidate = max(candidates, key=self._sort_key)
  File "c:\program files\python37\lib\site-packages\pip\_internal\index.py", line 710, in _sort_key
    has_allowed_hash = int(link.is_hash_allowed(self._hashes))
  File "c:\program files\python37\lib\site-packages\pip\_internal\models\link.py", line 213, in is_hash_allowed
    return hashes.is_hash_allowed(self.hash_name, hex_digest=self.hash)
AttributeError: 'NoneType' object has no attribute 'is_hash_allowed'

C:\WINDOWS\system32>pip list --uptodate
ERROR: Exception:
Traceback (most recent call last):
  File "c:\program files\python37\lib\site-packages\pip\_internal\cli\base_command.py", line 188, in main
    status = self.run(options, args)
  File "c:\program files\python37\lib\site-packages\pip\_internal\commands\list.py", line 158, in run
    packages = self.get_uptodate(packages, options)
  File "c:\program files\python37\lib\site-packages\pip\_internal\commands\list.py", line 170, in get_uptodate
    dist for dist in self.iter_packages_latest_infos(packages, options)
  File "c:\program files\python37\lib\site-packages\pip\_internal\commands\list.py", line 170, in <listcomp>
    dist for dist in self.iter_packages_latest_infos(packages, options)
  File "c:\program files\python37\lib\site-packages\pip\_internal\commands\list.py", line 195, in iter_packages_latest_infos
    best_candidate = evaluator.get_best_candidate(all_candidates)
  File "c:\program files\python37\lib\site-packages\pip\_internal\index.py", line 729, in get_best_candidate
    best_candidate = max(candidates, key=self._sort_key)
  File "c:\program files\python37\lib\site-packages\pip\_internal\index.py", line 710, in _sort_key
    has_allowed_hash = int(link.is_hash_allowed(self._hashes))
  File "c:\program files\python37\lib\site-packages\pip\_internal\models\link.py", line 213, in is_hash_allowed
    return hashes.is_hash_allowed(self.hash_name, hex_digest=self.hash)
AttributeError: 'NoneType' object has no attribute 'is_hash_allowed'

[landfillbaby]

duplicate of #6772