(WIP) ddar: fix python shebang location, add test, fix audit

[apjanke]

WIP. Please do not merge yet. I'm mainly PRing it so it can go through test-bot and CI.

Compare with other ddar WIP, #43358

[bfontaine]

It should be "#{bin}/ddar --help".

[apjanke]

Fixed.

[tdsmith]

We should install this to libexec and write wrapper scripts to add protobuf's modules to site-packages I guess. If we need to touch a faux __init__.py for the google namespace package while installing protobuf, we can; it should be harmless.

Vendoring the protobuf package sounds potentially nicer, actually.

Sorry, this all kinda sucks.

Distutils should actually already be rewriting the shebang so I don't think that inreplace is doing anything.

[apjanke]

You're right: if I remove that inreplace, then the shebang becomes #!/usr/local/opt/python/bin/python2.7. I'll remove the inreplace.

With this patch, all the ddar stuff does get installed to libexec, and a wrapper script to /usr/local/bin. But I don't think that's sufficient in itself.

I don't think we can successfully add protobuf and other brewed modules to site-packages with a wrapper script at run time. Some of those paths are defined using .pth files, which are only processed in directories which are in Python's site path based on their location in the filesystem. Adding dirs to PYTHONPATH only gets those particular directories on the path, and .pth files in them are not followed. E.g. the protobuf modules get on the path via /usr/local/lib/python2.7/site-packages/homebrew-protobuf.pth. So, from what I can tell, that site-packages dir needs to either be the primary site-packages dir for the python you're running it under, or included via another .pth file in one of the primary site-packages dirs.

What does "vendoring the protobuf package" mean?

[apjanke]

Here's an idea: would it be possible to wrap the program in a python wrapper script instead of a shell script, which checked the paths and called site.addsitedir to add the homebrew site-packages path if necessary, before running the main program in the same python instance? That way we maybe could add the site-packages directory at run time in a way that respected the .pth files in it.