Perl CPAN urllist reconfig

Reference:
http://major.io/2008/06/16/adjusting-cpan-mirror-list/

執行 cpan
Display your current mirrors:
cpan> o conf urllist

Delete the first mirror in your list:
cpan> o conf urllist shift

Delete the last mirror in your list:
cpan>  o conf urllist pop

Reconfig:
cpan> o conf init