use factory method for constructing Net::HTTP objects

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@34937 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/xmlrpc/client.rb

@@ -526,7 +526,7 @@ module XMLRPC
 
       if async
         # use a new HTTP object for each call
-        http = Net::HTTP.new(@host, @port, @proxy_host, @proxy_port)
+        http = net_http.new(@host, @port, @proxy_host, @proxy_port)
         http.use_ssl = @use_ssl if @use_ssl
         http.read_timeout = @timeout
         http.open_timeout = @timeout