Add special python args to subprocess patch

[nielstron]

Awesome project! I was recently adapting the patch utilities for subprocesses for a personal project and noticed that in some particular cases (i.e. when tracing tox) the patches don't work. The issue was resolved when I added the following python commands that take parameters (-X, -W and --check-hash-based-pycs) as special cases - otherwise their argument would be parsed as "script" parameter.

Example
python3 -X dev -m pytest would be split to python3 -X (patch-script) dev -m pytest instead of the correct python3 -X dev (patch-script) -m pytest.

[gaogaotiantian]

I don't have my dev machine near me recently so I'll have to test this myself later. However, I don't believe the solution is the right way to go. I believe the current regex is meant to detect the actual script part - so it should detect the -m pytest part and insert all the other py_args before -m. If it's not, then we should fix the regex, instead of adding an exception for a specific option. I believe it's because the file regex is too loose on detecting files.

[nielstron]

I see and I tried this before, however I think it's not so natural using the current approach. For example a valid parameterization for python is python3 -X dev.

The current approach splits the arguments by space and thus encounters first -X then dev. But it is perfectly possible that there is a script in the current directory with the filename dev. To distinguish the two you would need to suddenly look back in the arg history.

But feel free to try and implement it the other way around.

[gaogaotiantian]

Okay that makes sense. But in that case you probably need to take out all the dash options with arguments before identifying the file. I can work on this later when I finish my moving.

[gaogaotiantian]

Hi, sorry it took me so long to get back at this. I think the code should work fine. Do you mind adding a regression test for this?

[nielstron]

I'll have a look. Any suggestions on a related test case that I could adapt?

[gaogaotiantian]

It depends on how difficult it is to do a minimum repro. If you can repro this with a normal script on command line usage, checkout tests in test_cmdline.py, you can put the test in that file or test_regression.py. If it's hard to do it normally, check out test_patch.py, there are some coverage tests in that file to test corner cases. Or maybe you can do both :). I think in test_patch.py there are tests specifically for parsing subprocess args.