Wrap unsafe script shebangs in /bin/sh

[charliermarsh]

Summary

This is based on Pradyun's installer branch (https://github.com/pradyunsg/installer/blob/d01624e5f20963f046e67d58f5319e21a07aa03e/src/installer/scripts.py#L54), which is itself based on pip (https://github.com/pypa/pip/blob/0ad4c94be74cc24874c6feb5bb3c2152c398a18e/src/pip/_vendor/distlib/scripts.py#L136).

The gist of it is: on Posix platforms, if a path contains a space (or is too long), we wrap the shebang in a /bin/sh invocation.

Closes #2076.

Test Plan

❯ cargo run venv "foo"
    Finished dev [unoptimized + debuginfo] target(s) in 0.14s
     Running `target/debug/uv venv foo`
Using Python 3.12.0 interpreter at: /Users/crmarsh/.local/share/rtx/installs/python/3.12.0/bin/python3
Creating virtualenv at: foo
Activate with: source foo/bin/activate

❯ source "foo bar/bin/activate"

❯ which black
black not found

❯ cargo run pip install black
Resolved 6 packages in 177ms
Installed 6 packages in 17ms
 + black==24.2.0
 + click==8.1.7
 + mypy-extensions==1.0.0
 + packaging==23.2
 + pathspec==0.12.1
 + platformdirs==4.2.0

❯ which black
/Users/crmarsh/workspace/uv/foo bar/bin/black

❯ black
Usage: black [OPTIONS] SRC ...

One of 'SRC' or 'code' is required.

❯ cat "foo bar/bin/black"
#!/bin/sh
'''exec' '/Users/crmarsh/workspace/uv/foo bar/bin/python' "$0" "$@"
' '''
# -*- coding: utf-8 -*-
import re
import sys
from black import patched_main
if __name__ == "__main__":
    sys.argv[0] = re.sub(r"(-script\.pyw|\.exe)?$", "", sys.argv[0])
    sys.exit(patched_main())

[charliermarsh]

If we don't really care, we could remove the platform and OS casing. (I assume this is safe to do on Windows, just not required?)

[BurntSushi]

I would gently nudge toward using just one value at first and see if that causes any issues. I assume shebangs longer than 127 are pretty rare?

[charliermarsh]

Done!