emerge world
Calculating world dependencies /Traceback (most recent call last):
  File "/usr/bin/emerge", line 6047, in ?
    retval = emerge_main()
  File "/usr/bin/emerge", line 6041, in emerge_main
    myopts, myaction, myfiles, spinner)
  File "/usr/bin/emerge", line 5335, in action_build
    if not mydepgraph.xcreate(myaction):
  File "/usr/bin/emerge", line 2521, in xcreate
    if not self.select_dep(
  File "/usr/bin/emerge", line 1944, in select_dep
    myuse=selected_pkg[-1], rev_dep=rev_deps, arg=arg):
  File "/usr/bin/emerge", line 1445, in create
    parent_arg=arg):
  File "/usr/bin/emerge", line 1937, in select_dep
    rev_dep=rev_deps, arg=arg):
  File "/usr/bin/emerge", line 1445, in create
    parent_arg=arg):
  File "/usr/bin/emerge", line 1760, in select_dep
    self.pkgsettings[p_root].setinst(p_key, p_db)
  File "/usr/lib/portage/pym/portage.py", line 1815, in setinst
    provides = mydbapi.aux_get(mycpv, ["PROVIDE"])[0]
  File "/usr/lib/portage/pym/portage.py", line 5078, in aux_get
    raise KeyError(mycpv)
KeyError: 'sys-kernel/linux-headers-2.6.19.2-r2'