avoid recursion in rewrite, thanks Jonathan

gluon/rewrite.py

@@ -244,21 +244,15 @@ def try_rewrite_on_error(http_response, request, environ, ticket=None):
                     url = path_info + '?' + query_string
                     message = 'You are being redirected <a href="%s">here</a>'
                     return HTTP(303, message % url, Location=url), environ
-                else:
-                    error_raising_path = environ['PATH_INFO']
-                    # Rewrite routes_onerror path.
-                    path_info = '/' + path_info.lstrip(
-                        '/')  # add leading '/' if missing
-                    environ['PATH_INFO'] = path_info
-                    error_handling_path = \
-                        url_in(request, environ)[2]['PATH_INFO']
-                    # Avoid infinite loop.
-                    if error_handling_path != error_raising_path:
-                        # wsgibase will be called recursively with the routes_onerror path.
-                        environ['PATH_INFO'] = path_info
-                        environ['QUERY_STRING'] = query_string
-                        environ['WEB2PY_STATUS_CODE'] = status
-                        return None, environ
+                elif not environ.get('__ROUTES_ONERROR__', False):            
+                    # wsgibase will be called recursively with 
+                    # the routes_onerror path.
+                    environ['__ROUTES_ONERROR__'] = True # limit recursion
+                    path_info = '/' + path_info.lstrip('/')                   
+                    environ['PATH_INFO'] = path_info                           
+                    environ['QUERY_STRING'] = query_string                    
+                    environ['WEB2PY_STATUS_CODE'] = status
+                    return None, environ 
     # do nothing!
     return http_response, environ