Paths provided by -n are not normalized

[stephenfin]

Issue description

I attempted to run all tests in a file using the following:

tox -e functional-py310 -- -n nova//tests/functional/api_sample_tests/test_hosts.py

which run the following under the hood:

stestr --test-path=./nova/tests/functional run -n nova//tests/functional/api_sample_tests/test_hosts.py

Expected behavior and actual behavior

This should have run the tests in the file. Instead, it exited with this error:

==============================                                                                                                                                                    
Failed 1 tests - output below:                                                                                                                                                    
==============================                                                                                                                                                    
                                                                                                                                                                                  
unittest.loader._FailedTest.                                                                                                                                                      
----------------------------                                                                                                                                                      
                                                                                                                                                                                  
Captured traceback:                                                                                                                                                               
~~~~~~~~~~~~~~~~~~~                         
    ImportError: Failed to import test module: 
Traceback (most recent call last):
  File "/usr/lib64/python3.10/unittest/loader.py", line 154, in loadTestsFromName
    module = __import__(module_name)
ModuleNotFoundError: No module named 'nova.'

nova//tests/functional/api_sample_tests/test_hosts.py normalizes to nova/tests/functional/api_sample_tests/test_hosts.py (at least in Vim, Bash, and elsewhere) and stestr should be doing the same.

Steps to reproduce the problem

Per above.

Specifications like the version of the project, operating system, or hardware

n/a

System information

• OS: [e.g. Windows10, openSUSE 15.1, Ubuntu 18.04]: Fedora 40
• stestr version (stestr --version): stestr 4.1.0
• Python release (python --version): Python 3.10.14
• pip packages (pip freeze): n/a

Additional information

None.