Fix find_node issue with hash collisions

It could happen that when several keys produces the same hash that
find_node was not trying hard enough to traverse the rb tree.
Thanks to Markus Doppelbauer for his detailed bug report and test case.

Signed-off-by: Brice Figureau <brice@daysofwonder.com>

CHANGES

+nginx_upload_progress release 0.8.1                              27 Feb 2010
+
+ * Fixed find_node so that it can find correctly nodes when there is an
+ hash collision (thanks to Markus Doppelbauer for his detailed bug report
+ and test case).
+ 
 nginx_upload_progress release 0.8                                  19 Dec 2009
 
  * fixed segfault at start on some platforms (reported by Vladimir 

ngx_http_uploadprogress_module.c

 
         } while (node != sentinel && hash == node->key);
 
-        break;
+        /* found a key with unmatching hash (and value), let's keep comparing hashes then */
     }
     ngx_log_debug0(NGX_LOG_DEBUG_HTTP, log, 0, "upload-progress: can't find node");
     return NULL;