variable rv of type nsresult was not initialized in CreateInstance and in case of creating a StandardUrl with no Init in CreateInstance (and using rv) making it random to the calling function if creating the Url succeeded. This is what I thought was a namespace problem between necko and old netlib.

netwerk/build/nsNetFactory.cpp

@@ -75,7 +75,7 @@ nsNetFactory::CreateInstance(nsISupports *aOuter,
                              const nsIID &aIID,
                              void **aResult)
 {
-    nsresult rv;
+    nsresult rv = NS_OK;
 
     if (aResult == nsnull)
         return NS_ERROR_NULL_POINTER;