Traceback (most recent call last):
  File "/usr/bin/emerge", line 48, in <module>
    retval = emerge_main()
  File "/usr/lib64/portage/pym/_emerge/main.py", line 1044, in emerge_main
    gc_locals=locals().clear)
  File "/usr/lib64/portage/pym/_emerge/actions.py", line 3882, in run_action
    myopts, myaction, myfiles, spinner)
  File "/usr/lib64/portage/pym/_emerge/actions.py", line 310, in action_build
    settings, trees, myopts, myparams, myaction, myfiles, spinner)
  File "/usr/lib64/portage/pym/_emerge/depgraph.py", line 7337, in backtrack_depgraph
    myaction, myfiles, spinner)
  File "/usr/lib64/portage/pym/_emerge/depgraph.py", line 7369, in _backtrack_depgraph
    success, favorites = mydepgraph.select_files(myfiles)
  File "/usr/lib64/portage/pym/_emerge/depgraph.py", line 2576, in select_files
    return self._resolve(myfavorites)
  File "/usr/lib64/portage/pym/_emerge/depgraph.py", line 2717, in _resolve
    if not self._create_graph():
  File "/usr/lib64/portage/pym/_emerge/depgraph.py", line 1261, in _create_graph
    allow_unsatisfied=allow_unsatisfied):
  File "/usr/lib64/portage/pym/_emerge/depgraph.py", line 1814, in _add_pkg_deps
    allow_unsatisfied):
  File "/usr/lib64/portage/pym/_emerge/depgraph.py", line 1830, in _add_pkg_dep_string
    allow_unsatisfied)
  File "/usr/lib64/portage/pym/_emerge/depgraph.py", line 1875, in _wrapped_add_pkg_dep_string
    pkg, dep_priority, root_config, selected_atoms[pkg]):
  File "/usr/lib64/portage/pym/_emerge/depgraph.py", line 2081, in _minimize_children
    root_config.root, atom)
  File "/usr/lib64/portage/pym/_emerge/depgraph.py", line 3835, in _select_pkg_highest_available
    ret = self._select_pkg_highest_available_imp(root, atom, onlydeps=onlydeps)
  File "/usr/lib64/portage/pym/_emerge/depgraph.py", line 3976, in _select_pkg_highest_available_imp
    autounmask_level=autounmask_level)
  File "/usr/lib64/portage/pym/_emerge/depgraph.py", line 4369, in _wrapped_select_pkg_highest_available_imp
    use = self._pkg_use_enabled(pkg, target_use)
  File "/usr/lib64/portage/pym/_emerge/depgraph.py", line 4111, in _pkg_use_enabled
    real_flag = pkg.iuse.get_real_flag(flag)
  File "/usr/lib64/portage/pym/_emerge/Package.py", line 653, in get_real_flag
    (flag, self._pkg.cpv, self._pkg.repo))
ValueError: 'xpdf-headers' flag is not in IUSE and is not an alias of any flag in IUSE of 'app-text/poppler-0.20.5::gentoo'