> Because there’s no good place to stick a pdb/breakpoint to debug such issues other than site.py, and that usually requires sudo.

Something bad was installed with sudo but suddenly sudo is not acceptable for debugging? This seems crazy.

How exactly are pth files hard to debug? Are those files hard to edit? They sure are, but the problem ain't the point where they are run, it's the fact that a big lump of code is stuffed on a single line. Lets fix that instead!

I've written pth files with lots of stuff in them, and my experience is quite the opposite - they help with debugging. A lot. It's an incredibly useful python feature.

> I don’t remember the details, but yes I have been caught in this trap. 

Maybe if you remember the details we can discuss what are the debugging options, and what can be improved.