Fall back to a cpan mirror if cpan-rsync.perl.org is down
Fall back to a cpan mirror if cpan-rsync.perl.org is down

I just selected a single one in germany, since the
modules.perl6.org server will again be deployed there,
but at a future point we could probably grab the
mirrors list (as json) from cpan and grab a couple
of random ones to try.

perl6/modules.perl6.org,perl6/modules.perl6.org,perl6/modules.perl6.org,perl6/modules.perl6.org