OSX 10.10 select perl 5.16 instead of 5.18
You should be able to do this with either of the following commands:
defaults write com.apple.versioner.perl Version -string 5.16
or
export VERSIONER_PERL_VERSION=5.16
These are not system wide settings and only affect the user setting them.
Sources: http://krypted.com/mac-os-x/perl-control/ and https://gist.github.com/crankycoder/1389144