Fix url.format usage of path on node@0.11.15

node@0.11.15 was released with a patch that adds support for `path` to
url.format
(d312b6d15c).

However, this broke `npm install` for git+ssh urls and as such has been
reverted on io.js, making it work like on node@0.11.14 again.

913addbff5

lib/request.js

@@ -117,6 +117,8 @@ module.exports = {
   set path(path) {
     var url = parse(this.req);
     url.pathname = path;
+    url.path = null;
+
     this.url = stringify(url);
   },
 
@@ -167,6 +169,8 @@ module.exports = {
   set querystring(str) {
     var url = parse(this.req);
     url.search = str;
+    url.path = null;
+
     this.url = stringify(url);
   },