lamusic ~ % sudo emerge -avuDN world

These are the packages that would be merged, in order:

Calculating world dependencies \
!!! All ebuilds that could satisfy "media-gfx/openscenegraph" have been masked.
!!! One of the following masked packages is required to complete your request:
Traceback (most recent call last):
  File "/usr/bin/emerge", line 6506, in <module>
    retval = emerge_main()
  File "/usr/bin/emerge", line 6500, in emerge_main
    myopts, myaction, myfiles, spinner)
  File "/usr/bin/emerge", line 5802, in action_build
    if not mydepgraph.xcreate(myaction):
  File "/usr/bin/emerge", line 2635, in xcreate
    self.target_root, mydep, raise_on_missing=True, arg=mydep):
  File "/usr/bin/emerge", line 2063, in select_dep
    metadata=selected_pkg[1], rev_dep=rev_deps, arg=arg):
  File "/usr/bin/emerge", line 1495, in create
    parent_arg=arg):
  File "/usr/bin/emerge", line 1973, in select_dep
    settings=pkgsettings, portdb=portdb)
  File "/usr/lib64/portage/pym/portage.py", line 5124, in getmaskingstatus
    raise KeyError("CPV %s does not exist" % mycpv)
KeyError: 'CPV media-gfx/openscenegraph-2.0 does not exist'