errno.c: hide internal `_sys_fail` from backtrace.
@@ -92,6 +92,7 @@ mrb_sce_sys_fail(mrb_state *mrb, mrb_value cls)
int argc;
char name[8];
+ mrb->c->ci->mid = 0;
sce = mrb_class_get(mrb, "SystemCallError");
argc = mrb_get_args(mrb, "i|S", &no, &msg);
if (argc == 1) {
