Incompatible versions when using ~= with truncated versions

[adriangonz]

Description

It seems that the latest version of pip has some issues resolving packages which have multiple "compatible release" (i.e. ~=) version specifications, particularly if some of them are truncated. For example, six ~= 1.15 and six ~= 1.15.0 (e.g. pip install six~=1.15 six~=1.15.0).

The result is that pip will fail with an InconsistentCandidate exception (see full output below).

This seems to have been introduced with, at least, pip == 21.3.1. We're not able to reproduce it with pip == 21.2.4.

Expected behavior

Following the example above, each of those requirements should be equivalent to:

• six ~= 1.15, equivalent to six >= 1.15, == 1.*
• six ~= 1.15.0, equivalent to six >= 1.15.0, == 1.15.*

Therefore, pip should be able to identify any six == 1.15.x release as compatible.

pip version

21.3.1

Python version

3.7.12

OS

Linux

How to Reproduce

1. Try to install pip install six~=1.15 six~=1.15.0.
2. Pip will fail with an InconsistentCandidate exception.

Output

$ pip install six~=1.15 six~=1.15.0

Collecting six~=1.15
  Using cached six-1.16.0-py2.py3-none-any.whl (11 kB)
ERROR: Exception:
Traceback (most recent call last):
  File "/home/agm/.virtualenvs/test/lib/python3.7/site-packages/pip/_internal/cli/base_command.py", line 164, in exc_logging_wrapper
    status = run_func(*args)
  File "/home/agm/.virtualenvs/test/lib/python3.7/site-packages/pip/_internal/cli/req_command.py", line 205, in wrapper
    return func(self, options, args)
  File "/home/agm/.virtualenvs/test/lib/python3.7/site-packages/pip/_internal/commands/install.py", line 339, in run
    reqs, check_supported_wheels=not options.target_dir
  File "/home/agm/.virtualenvs/test/lib/python3.7/site-packages/pip/_internal/resolution/resolvelib/resolver.py", line 93, in resolve
    collected.requirements, max_rounds=try_to_avoid_resolution_too_deep
  File "/home/agm/.virtualenvs/test/lib/python3.7/site-packages/pip/_vendor/resolvelib/resolvers.py", line 482, in resolve
    state = resolution.resolve(requirements, max_rounds=max_rounds)
  File "/home/agm/.virtualenvs/test/lib/python3.7/site-packages/pip/_vendor/resolvelib/resolvers.py", line 374, in resolve
    failure_causes = self._attempt_to_pin_criterion(name)
  File "/home/agm/.virtualenvs/test/lib/python3.7/site-packages/pip/_vendor/resolvelib/resolvers.py", line 228, in _attempt_to_pin_criterion
    raise InconsistentCandidate(candidate, criterion)
pip._vendor.resolvelib.resolvers.InconsistentCandidate: Provided candidate LinkCandidate('https://files.pythonhosted.org/packages/d9/5a/e7c31adbe875f2abbb91bd84cf2dc52d792b5a01506781dbcf25c91daf11/six-1.16.0-py2.py3-none-any.whl#sha256=8abb2f1d86890a2dfb989f9a77cfcfd3e47c2a354b01111771326f8aa26e0254 (from https://pypi.org/simple/six/) (requires-python:>=2.7, !=3.0.*, !=3.1.*, !=3.2.*)') does not satisfy SpecifierRequirement('six~=1.15'), SpecifierRequirement('six~=1.15.0')

Code of Conduct

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[adriangonz]

Closing as it seems a duplicate of #9613