ref https://bugs.launchpad.net/zc.buildout/+bug/144228 .
In shutil.rmtree, I can't find any call to onerror(os.lstat, ...). I think this second case can be dropped.
shutil.rmtree
onerror(os.lstat, ...)
Perhaps because Python 3 uses it. In this case, the exception should be reraised if it's not a link.