Simon Budig's patch (posted by me):
[ #513235 ] prevent readline filename completion
diff --git a/Modules/readline.c b/Modules/readline.c
index fa4fc06..9b4d952 100644
--- a/Modules/readline.c
+++ b/Modules/readline.c
@@ -460,6 +460,9 @@
lock released! */
save_tstate = PyThreadState_Swap(NULL);
PyEval_RestoreThread(completer_tstate);
+ /* Don't use the default filename completion if we
+ * have a custom completion function... */
+ rl_attempted_completion_over = 1;
r = PyObject_CallFunction(completer, "si", text, state);
if (r == NULL)
goto error;