# emerge world -uDNav --with-bdeps=y

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

Calculating dependencies... done!

!!! The ebuild selected to satisfy ">=media-sound/gnome-music-3.14.0" has unmet requirements.
- media-sound/gnome-music-3.14.3.1::gentoo USE="" PYTHON_SINGLE_TARGET="python3_3 python3_4" PYTHON_TARGETS="python3_3 -python3_4"

  The following REQUIRED_USE flag constraints are unsatisfied:
    exactly-one-of ( python_single_target_python3_3 python_single_target_python3_4 ) python_single_target_python3_4? ( python_targets_python3_4 )

  The above constraints are a subset of the following complete expression:
    exactly-one-of ( python_single_target_python3_3 python_single_target_python3_4 ) python_single_target_python3_3? ( python_targets_python3_3 ) python_single_target_python3_4? ( python_targets_python3_4 )

(dependency required by "gnome-base/gnome-extra-apps-3.14.1-r1" [installed])
(dependency required by "gnome-base/gnome-3.14.1[extras]" [installed])
(dependency required by "@selected" [set])
(dependency required by "@world" [argument])