Discover python in a case insensitive way

[xavfernandez]

Thanks your impressive work on the rewrite !

Everything works fine on my part but was actually surprised by:

$ virtualenv20 --version
virtualenv 20.0.3 from /home/xafer/.local/bin/virtualenv20/virtualenv/__init__.py

$ virtualenv20 -p cpython3.7 test
Traceback (most recent call last):
  File "/usr/lib/python3.8/runpy.py", line 193, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/usr/lib/python3.8/runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "/home/xafer/.local/bin/virtualenv20/__main__.py", line 169, in <module>
  File "/home/xafer/.local/bin/virtualenv20/__main__.py", line 165, in run
  File "/home/xafer/.local/bin/virtualenv20/virtualenv/__main__.py", line 19, in run
  File "/home/xafer/.local/bin/virtualenv20/virtualenv/run/__init__.py", line 22, in cli_run
  File "/home/xafer/.local/bin/virtualenv20/virtualenv/run/__init__.py", line 29, in session_via_cli
  File "/home/xafer/.local/bin/virtualenv20/virtualenv/run/__init__.py", line 51, in build_parser
RuntimeError: failed to find interpreter for Builtin discover of python_spec='cpython3.7'

$ virtualenv20 -p CPython3.7 test
created virtual environment in 82ms CPython3Posix(dest=/home/xafer/tmp/test, clear=False, global=False) with seeder FromAppData pip=latest setuptools=latest wheel=latest app_data_dir=/home/xafer/.local/share/virtualenv/seed-v1 via=copy

IMHO the interpreter discovery shouldn't consider the case.

[gaborbernat]

@xavfernandez makes sense, feels like an oversight 👍

[PrajwalM2212]

I would like to work on this.

[ssbarnea]

I think it would be wrong to be case insensitive. Most platforms are case-insensitive. Even MacOS switched to defaulting to case-insensitive in recent years.

If you give a param, you better know what you type.

[gaborbernat]

Hello, a fix for this issue has been released via virtualenv 20.0.5; see https://pypi.org/project/virtualenv/20.0.5/ (https://virtualenv.pypa.io/en/latest/changelog.html#v20-0-5-2020-02-21) . Please give a try and report back if your issue has not been addressed; if not, please comment here, and we'll reopen the ticket. We want to apologize for the inconvenience this has caused you and say thanks for having patience while we resolve the unexpected bugs with this new major release.