Nevertheless GNUstep should handle this. Either by changing
NSTemporaryDirectory() or by hacking openStepPathFromLocal and/or
stringByStandardizingPath.
I guess the task of GNUstep is to encapsulate all this awful operating
system functions. So GNUstep have be to hacked.
I don't understand your reasoning here.
The NSTemporaryDirectory() function is supposed to supply the name of a
temporary directory that your program can use to store its own private
temporary files in. You are not supposed to make any assumption about where
this temporary directory is. This path is not (and should not be) user-visible
in any way, and so as long as it works there is, as far as I can see, no
reason why it should look like anything in particular (certainly code should
not rely on it being any particular directory).