I'm -1 to the library ignore errors without specific indication from the
user, specially when it's so easy to do it in the calling code.

We agree that copytree could grow an option like the one in os.walk.
Feel free to open an issue for it (this discussion went through other
path here, that's why I prefer a clean issue; you should refer this one
in the text, though). You should first discuss this in the list, also.

Thank you!