There are two problems with your code and bug report:

1. By using a single quoted string, some of the backslashes in the path are being interpreted as starting a special character (specifically \t is interpreted as a tab character). You should either double the backslashes to prevent this interpretation (dir_path='d:\\c\\d\\e\\t\\c\\t.xf'), use forward slashes (dir_path='d:/c/d/e/t/c/t.xf') or use a raw string (dir_path=r'd:\c\d\e\t\c\t.xf').

2. You're reporting that Python "auto adds \". It doesn't, it's just that the repr of the string shows a single quoted string with backslashes doubled - that's the standard repr for strings.

So, Python is behaving as expected, and there's no bug here.