emerge -avuDN world  
Traceback (most recent call last):
  File "/usr/lib/python-exec/python3.4/emerge", line 50, in <module>
    retval = emerge_main()
  File "/usr/lib64/python3.4/site-packages/_emerge/main.py", line 1224, in emerge_main
    return run_action(emerge_config)
  File "/usr/lib64/python3.4/site-packages/_emerge/actions.py", line 3261, in run_action
    retval = action_build(emerge_config, spinner=spinner)
  File "/usr/lib64/python3.4/site-packages/_emerge/actions.py", line 338, in action_build
    settings, trees, myopts, myparams, myaction, myfiles, spinner)
  File "/usr/lib64/python3.4/site-packages/_emerge/depgraph.py", line 9247, in backtrack_depgraph
    myaction, myfiles, spinner)
  File "/usr/lib64/python3.4/site-packages/_emerge/depgraph.py", line 9284, in _backtrack_depgraph
    success, favorites = mydepgraph.select_files(myfiles)
  File "/usr/lib64/python3.4/site-packages/_emerge/depgraph.py", line 3606, in select_files
    return self._select_files(args)
  File "/usr/lib64/python3.4/site-packages/_emerge/depgraph.py", line 3949, in _select_files
    return self._resolve(myfavorites)
  File "/usr/lib64/python3.4/site-packages/_emerge/depgraph.py", line 4100, in _resolve
    if not self._create_graph():
  File "/usr/lib64/python3.4/site-packages/_emerge/depgraph.py", line 2401, in _create_graph
    allow_unsatisfied=allow_unsatisfied):
  File "/usr/lib64/python3.4/site-packages/_emerge/depgraph.py", line 3112, in _add_pkg_deps
    allow_unsatisfied):
  File "/usr/lib64/python3.4/site-packages/_emerge/depgraph.py", line 3128, in _add_pkg_dep_string
    allow_unsatisfied)
  File "/usr/lib64/python3.4/site-packages/_emerge/depgraph.py", line 3208, in _wrapped_add_pkg_dep_string
    pkg, dep_priority, root_config, selected_atoms[pkg]):
  File "/usr/lib64/python3.4/site-packages/_emerge/depgraph.py", line 3407, in _minimize_children
    root_config.root, atom, parent=parent)
  File "/usr/lib64/python3.4/site-packages/_emerge/depgraph.py", line 5364, in _select_pkg_highest_available
    ret = self._select_pkg_highest_available_imp(root, atom, onlydeps=onlydeps, parent=parent)
  File "/usr/lib64/python3.4/site-packages/_emerge/depgraph.py", line 5576, in _select_pkg_highest_available_imp
    root, atom, onlydeps=onlydeps, parent=parent)
  File "/usr/lib64/python3.4/site-packages/_emerge/depgraph.py", line 5872, in _wrapped_select_pkg_highest_available_imp
    onlydeps=onlydeps):
  File "/usr/lib64/python3.4/site-packages/_emerge/depgraph.py", line 5282, in _iter_match_pkgs_atom
    installed=installed, onlydeps=onlydeps, myrepo=repo)
  File "/usr/lib64/python3.4/site-packages/_emerge/depgraph.py", line 6580, in _pkg
    if not self._pkg_visibility_check(pkg) and \
  File "/usr/lib64/python3.4/site-packages/_emerge/depgraph.py", line 5620, in _pkg_visibility_check
    if pkg.visible:
  File "/usr/lib64/python3.4/site-packages/_emerge/Package.py", line 177, in visible
    self._visible = self._eval_visiblity(self.masks)
  File "/usr/lib64/python3.4/site-packages/_emerge/Package.py", line 171, in masks
    self._masks = self._eval_masks()
  File "/usr/lib64/python3.4/site-packages/_emerge/Package.py", line 403, in _eval_masks
    self.cpv, self._metadata)
  File "/usr/lib64/python3.4/site-packages/portage/package/ebuild/config.py", line 2041, in _getMissingLicenses
    cpv, metadata["USE"], metadata["LICENSE"], metadata["SLOT"], metadata.get('repository'))
  File "/usr/lib64/python3.4/site-packages/_emerge/Package.py", line 872, in __getitem__
    v = self._pkg._init_use()
  File "/usr/lib64/python3.4/site-packages/_emerge/Package.py", line 664, in _init_use
    use_str = self._get_pkgsettings()["PORTAGE_USE"]
  File "/usr/lib64/python3.4/site-packages/_emerge/Package.py", line 639, in _get_pkgsettings
    pkgsettings.setcpv(self)
  File "/usr/lib64/python3.4/site-packages/portage/package/ebuild/config.py", line 1384, in wrapper
    return f(self, *args, **kwargs)
  File "/usr/lib64/python3.4/site-packages/portage/package/ebuild/config.py", line 1559, in setcpv
    self.puse = self._use_manager.getPUSE(cpv_slot)
  File "/usr/lib64/python3.4/site-packages/portage/package/ebuild/_config/UseManager.py", line 555, in getPUSE
    puse_matches = ordered_by_atom_specificity(cpdict, pkg)
  File "/usr/lib64/python3.4/site-packages/portage/package/ebuild/_config/helper.py", line 34, in ordered_by_atom_specificity
    bestmatch = best_match_to_list(pkg, keys)
  File "/usr/lib64/python3.4/site-packages/portage/dep/__init__.py", line 2058, in best_match_to_list
    for x in match_to_list(mypkg, mylist):
  File "/usr/lib64/python3.4/site-packages/portage/dep/__init__.py", line 2026, in match_to_list
    if x not in matches and match_from_list(x, pkgs):
  File "/usr/lib64/python3.4/site-packages/portage/dep/__init__.py", line 2341, in match_from_list
    use = getattr(x, "use", None)
  File "/usr/lib64/python3.4/site-packages/_emerge/Package.py", line 633, in use
    self._init_use()
  File "/usr/lib64/python3.4/site-packages/_emerge/Package.py", line 664, in _init_use
    use_str = self._get_pkgsettings()["PORTAGE_USE"]
  File "/usr/lib64/python3.4/site-packages/_emerge/Package.py", line 639, in _get_pkgsettings
    pkgsettings.setcpv(self)
  File "/usr/lib64/python3.4/site-packages/portage/package/ebuild/config.py", line 1381, in wrapper
    raise AssertionError('setcpv recursion detected')
AssertionError: setcpv recursion detected