ping @Araq
or the new getHomeDir variant shall be renamed?

The code is ugly.

but that's how CPython implemented it (if you refer to body of getHomeDir(username: string)?)

Why would I care how CPython does things... We need to live with this code for good, so clean it up so that the control flow doesn't look like it came from hell.

Why would I care how CPython does things...

Sure. I just mean there's an implementation doing so, which has alreadly reviewed by many contributors

clean it up so that the control flow doesn't look like it came from hell.

If referring to the condition compile branch,
I never wanna make it a hell either... But it's the fact that:

1. some posix like Mac lacks SC_GETPW_R_SIZE_MAX
2. some platform lacks dynamic memory allocate functions.

Also I used to have a try but have no idea.
Pointing out which part requires amend would be helpful.