There is an ongoing outage on the primary CPAN mirror. It is possible to work around the issue by using MetaCPAN as a mirror.

ALEXP / FormValidator-Simple-Plugin-CustomConstraint-0.01 / Changes 
Revision history for Perl extension FormValidator::Simple::Plugin::CustomConstraint.

0.01  Sat Apr 28 05:40:48 2012
  - first version created