clear http->send_buffer when we have freed the memory it pointed to
diff --git a/lib/http.c b/lib/http.c
index b361a20..7f6752e 100644
--- a/lib/http.c
+++ b/lib/http.c
@@ -624,6 +624,7 @@
     
     free(buff->buffer);
     free(buff);
+    http->send_buffer = NULL; /* cleaer the pointer */
   }
 
   if(HTTPREQ_POST_FORM == data->set.httpreq) {