I just installed 5.005_03 for testing. It came with an earlier version of CPAN, of course. I tried to update a few modules, and they kept trying to install Perl 5.6.1. Then I updated to v1.59, and am now getting messages like:

cpan> install Cwd
Running install for module Cwd
Running make for G/GS/GSAR/perl-5.6.0.tar.gz
 
The most recent version "2.02" of the module "Cwd"
comes with the current version of perl (5.6.0).
I'll build that only if you ask for something like
    force install Cwd
or
    install G/GS/GSAR/perl-5.6.0.tar.gz
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