Revert "http: don't bother making a copy of the options"

This reverts commit 06cfff9.

Reverted because it introduced a regression where (because options were
modified in the later functionality) options.host and options.port would
be overridden with values provided in other, supported ways.

PR-URL: nodejs#1467
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

lib/_http_client.js

@@ -21,6 +21,8 @@ function ClientRequest(options, cb) {
 
   if (typeof options === 'string') {
     options = url.parse(options);
+  } else {
+    options = util._extend({}, options);
   }
 
   var agent = options.agent;