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

Calculating dependencies ... done!
Dependency resolution took 0.88 s (backtrack: 0/20).


!!! The ebuild selected to satisfy "sys-apps/accountsservice" has unmet requirements.
- sys-apps/accountsservice-26.27.3::gentoo USE="-doc -elogind -gtk-doc -introspection (-selinux) (-systemd) -test -vala -xcrypt"

  The following REQUIRED_USE flag constraints are unsatisfied:
    exactly-one-of ( elogind systemd )

(dependency required by "x11-misc/mugshot-0.4.3-r2::gentoo" [ebuild])
(dependency required by "=x11-misc/mugshot-0.4.3-r2" [argument])