report the failing format_char for unimplemented String#% formats
@@ -50,7 +50,7 @@ class StringFormatter(object):
result_w.append(w_res)
break
else:
- raise space.error(space.w_NotImplementedError)
+ raise space.error(space.w_NotImplementedError, "%%%s" % format_char)
return result_w
def _next_item(self):
