The package still used python-six. Luckily a PR was ready for its
removal.
* gnu/packages/python-xyz.scm (python-treelib)[source]: Add patch.
* gnu/packages/patches/python-treelib-remove-python2-compat.patch: Add file.
* gnu/local.mk: Record patch.
Change-Id: I91a37770391cc72f158ade5b9619e80ab9a36bc7
Signed-off-by: Sharlatan Hellseher <sharlatanus@gmail.com>
