Drop Python built-in pwd module support

[ryanking13]

This PR drops Python built-in pwd module support.
The pwd module is a Unix specific module which provides access to unix user account and passwd database.

Emscripten does not support pwd related syscalls (there is no user account in browser environment),
so currently calling pwd methods raises an error:

As CPython supports non-Unix environments (e.g. Windows), I believe dropping pwd module will cause no bad side effects.
I looked for some cases where CPython import pwd module. It handles error when pwd module is not available:

• pathlib
• shutil
• http

Note that other Unix specific modules like grp, spwd, syslog are already not included in pyodide.

This resolves #1857, so I think this is a fix.

[hoodmane]

Thanks @ryanking13!

I was wondering if you could use Setup.local to do this rather than patching Setup but I found the following text in the docs:

you'll still have to edit Setup if you want to disable modules that are enabled by default, or if such modules need non-standard options.

Not sure if this is current info but I think it is and it means this is the right way to get rid of pwd.

[ryanking13]

@hoodmane Thanks for the suggestion!

I was wondering if you could use Setup.local to do this rather than patching Setup

Maybe it is possible with a custom Setup.local file with disabled option.

I'll check whether it is possible.

# https://github.com/python/cpython/blob/3d1ca867ed0e3ae343166806f8ddd9739e568ab4/Modules/Setup#L19-L21
# Modules are not built at all, not by the Makefile,
# nor by the setup.py script, when they are preceded by a "*disabled*" tag
# line.

[ryanking13]

Maybe it is possible with a custom Setup.local file with disabled option.

Well, I tested it, and sadly adding *disabled* option in Setup.local doesn't disable modules in Modules/Setup.
(It affects modules in setup.py, but not in Modules/Setup)

I'm not sure this is intended behavior or a bug.
But for now, I think patching Modules/Setup is the only way to get rid of core built-in modules like pwd.

[hoodmane]

Thanks for checking.

[rth]

Thanks @ryanking13 ! Please add it to the docs otherwise LGTM.

[ryanking13]

@rth Updated docs!