-#!/usr/bin/perl +#!/bin/sh Just to mention that an alternative would be #!/usr/bin/env perl.
I don't know about obscure systems that gnulib may be targeting, but we've used /usr/bin/env for years in TeX Live and elsewhere, so it at least works on a reasonably wide range of systems (GNU, *BSD, *Solaris, AIX, Darwin, HP-UX, etc.).