Makefile.PL wrapper chmod arg

I noticed Makefile.PL 'chmod's squid_wrapper with +s argument. It means 'ug+s' implicitly and the wrapper became 6755(rwsr_sr_s or setuidgid-root). There's inconsistency between Manual install section of README. Does it need setgid?
Merge pull request #19 from darold/wrapper-setuid-fix

Makefile.PL wrapper chmod arg