test_gem_remote_fetcher.rb: stop SSL server

* test/rubygems/test_gem_remote_fetcher.rb (stop_servers): stop
  SSL server before shutdown its thread.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46640 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/rubygems/test_gem_remote_fetcher.rb

@@ -723,9 +723,13 @@ gems:
         @proxy_server = nil
       end
       if @ssl_server
-        @ssl_server.kill.join
+        @ssl_server.stop
         @ssl_server = nil
       end
+      if @ssl_server_thread
+        @ssl_server_thread.kill.join
+        @ssl_server_thread = nil
+      end
     end
 
     def normal_server_port
@@ -776,7 +780,8 @@ gems:
           raise
         end
       end
-      @ssl_server = t
+      @ssl_server = server
+      @ssl_server_thread = t
       server
     end