Backport AsyncHttpClient#272

Author: Stephane Landelle

src/main/java/com/ning/http/client/RequestBuilderBase.java

@@ -371,6 +371,8 @@ protected RequestBuilderBase(Class<T> derived, Request prototype) {
 
     public T setUrl(String url) {
         request.originalUri = buildURI(url);
+        request.uri = null;
+        request.rawUri = null;
         return derived.cast(this);
     }