The problem is that in the current implementation there is no hook to
allow overriding any setup prior to exec, so the only way to produce the
standard UNIX behavior assumed by many scripts is to copy-paste the code
and patch it manually, which is very crude and defeats the whole idea of
including it in the standard library.

Part of the problem is that the CGI spec isn't properly documented. A
great many early Internet standards were slapdashedly written up by
Netscape on web sites that were dropped by AOL eventually.