[ https://bugs.python.org/issue24564#msg246278 ]

> Adding `EINVAL` to the ignored errnos would fix the problem, but might hide real failures (I'm not sure about the real failures, but it seems logical).

I think this is an acceptable compromise considering that:

1) because of this the copy operation will ultimately fail (despite file will be copied)
2) there is nothing we can do except emit a warning somehow 
3) EPERM and ENODATA are already silently ignored (also ENOTSUP but that is more legit)

For completeness, other than copytree() also copy2() and move() are affected. 
I submitted a PR: https://github.com/python/cpython/pull/8601.