Carmel doesn't support dist/url/mirror per module

[miyagawa]

At some point Carmel stopped passing the cpanfile as-is to Menlo in most install/update commands, and do this by recreating all the required modules by querying CPAN and restoring from the snapshot, and re-encoding them to another cpanfile. This seems to make it so that the options like dist and url in cpanfile are lost during the conversion.

This makes it harder to patch broken CPAN distribution by pointing to a patched tarball either locally or at a company DarkPAN e.g.

requires 'Foo', '1', url => "https://darkpan.example.com/Foo-1.00.tar.gz";