bpo-20849: allow existing directory in shutil.copytree by ofek · Pull Request #2977 · python/cpython
@ofek Thanks for the PR and sorry that it has languished. But the PR cannot be accepted as is for two reasons: one, it ignores the discussion on the bug tracker about why changing the semantics of shutil.copytree to unconditionally ignore existing destination directories may be problematic; and two, we require PRs to be submitted against the cpython master branch, not a maintenance branch like 3.6; if a core developer decides to accept and merge a PR against master, they will decide whether any backports to maintenance branches are appropriate. Thus, I am closing the PR against 3.6. If you are still interested in pursuing this, perhaps making a new PR against master from the originally submitted patch might be a way forward.