Use %Module::CoreList::bug_tracker to print out upstream bug tracker …

…URLs.

Where the user names a module that their bug report is about, and we know the
URL for its upstream bug tracker, provide a message to the user explaining
that the core copies the CPAN version directly, and provide the URL for
reporting the bug directly to upstream.

utils/perlbug.PL

@@ -603,6 +603,12 @@ its name correctly. If it is correct, quit this program, try searching
 for $entry on http://rt.cpan.org, and report your issue there.
 EOF
 
+            $entry = '';
+	} elsif (my $bug_tracker = $Module::CoreList::bug_tracker{$entry}) {
+		paraprint <<"EOF";
+$entry included with core Perl is copied directly from the CPAN distribution.
+Please report bugs in $entry directly to its maintainers using $bug_tracker
+EOF
             $entry = '';
         } elsif ($entry) {
 	        $category ||= 'library';