Consider code:

for (root, dirs, nondirs) in os.walk(path, followlinks=False):
    print (nondirs)

This code will not print symlinks that refer to some dir. I think it is the bug.

In other words: If followlinks is True, we should consider some symlinks as dirs. If not, any symlink is the non-dir.

Patch included.

Also, please fix documentation about this nuance.