$OpenBSD: patch-lib_rubygems_remote_fetcher_rb,v 1.3 2017/09/02 21:32:07 jeremy Exp $

Index: lib/rubygems/remote_fetcher.rb
--- lib/rubygems/remote_fetcher.rb.orig
+++ lib/rubygems/remote_fetcher.rb
@@ -92,7 +92,7 @@ class Gem::RemoteFetcher
     else
       target = res.target.to_s.strip
 
-      if /\.#{Regexp.quote(host)}\z/ =~ target
+      if URI("http://" + target).host.end_with?(".#{host}")
         return URI.parse "#{uri.scheme}://#{target}#{uri.path}"
       end
 
