Many of the spec test files warn about this, e.g.:
*** Can't locate Pugs/Runtime/Match/HsBridge.pm in @INC (@INC contains: /home/coke/.cabal/share/Pugs-6.2.13.20120717/blib6/pugs/perl5/lib /home/coke/.cabal/share/Pugs-6.2.13.20120717/blib6/pugs/perl5/lib /home/coke/.cabal/share/Pugs-6.2.13.20120717/blib6/pugs/perl5/lib /home/coke/perl5/perlbrew/perls/perl-5.14.2/lib/site_perl/5.14.2/x86_64-linux-thread-multi /home/coke/perl5/perlbrew/perls/perl-5.14.2/lib/site_perl/5.14.2 /home/coke/perl5/perlbrew/perls/perl-5.14.2/lib/5.14.2/x86_64-linux-thread-multi /home/coke/perl5/perlbrew/perls/perl-5.14.2/lib/5.14.2 .) at (eval 7) line 1.