Bug #75332 for Module-Install: MI Encourages users to use the nonstandard "gpl2" when it should be "gpl_2"

    gpl          => 'http://opensource.org/licenses/gpl-license.php',
    gpl2         => 'http://opensource.org/licenses/gpl-2.0.php',
    gpl3         => 'http://opensource.org/licenses/gpl-3.0.html',

...

sub license {
        my $self = shift;
        return $self->{values}->{license} unless @_;
        my $license = shift or die(
                'Did not provide a value to license()'
        );
        $license = __extract_license($license) || lc $license;
        $self->{values}->{license} = $license;

        # Automatically fill in license URLs
        if ( $license_urls{$license} ) {
                $self->resources( license => $license_urls{$license} );
        }

        return 1;
}