"pip show" fails when used on different disk from pip installation

[JAK0723]

Description

Using the "show" command on any disk other than the one where python/pip is installed will result in an error. This bug was introduced in 21.2, it does not occur when using 21.1.3.

Expected behavior

The show command works normally, displaying information about the specified package.

pip version

21.2.1

Python version

3.9.6

OS

Windows 10 Build 19043.1110

How to Reproduce

1. Open a terminal on a disk different from the disk where python and/or pip is installed.
2. Then run pip show pip.
3. Produces a ValueError.

Output

E:\> pip show pip
ERROR: Exception:
Traceback (most recent call last):
  File "c:\python\python39\lib\site-packages\pip\_internal\cli\base_command.py", line 173, in _main
    status = self.run(options, args)
  File "c:\python\python39\lib\site-packages\pip\_internal\commands\show.py", line 45, in run
    if not print_results(
  File "c:\python\python39\lib\site-packages\pip\_internal\commands\show.py", line 160, in print_results
    for i, dist in enumerate(distributions):
  File "c:\python\python39\lib\site-packages\pip\_internal\commands\show.py", line 128, in search_packages_info
    files = sorted(os.path.relpath(p, dist.location) for p in files_iter)
  File "c:\python\python39\lib\site-packages\pip\_internal\commands\show.py", line 128, in <genexpr>
    files = sorted(os.path.relpath(p, dist.location) for p in files_iter)
  File "c:\python\python39\lib\ntpath.py", line 703, in relpath
    raise ValueError("path is on mount %r, start on mount %r" % (
ValueError: path is on mount 'E:', start on mount 'c:'

Code of Conduct

• I agree to follow the PSF Code of Conduct.

[bschnei]

I believe this is related to #10204

[uranusjr]

Agreed. I’m going to close this for now. Please reopen if you still encounter this in 21.2.2 (should drop in a day or two).