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

Calculating dependencies ...

!!! Problem resolving dependencies for =app-admin/lsyncd-2.3.1
 done!
Dependency resolution took 0.84 s (backtrack: 0/20).


!!! The ebuild selected to satisfy "=app-admin/lsyncd-2.3.1" has unmet requirements.
- app-admin/lsyncd-2.3.1::gentoo USE="" LUA_SINGLE_TARGET="-lua5-3 -lua5-4"

  The following REQUIRED_USE flag constraints are unsatisfied:
    exactly-one-of ( lua_single_target_lua5-3 lua_single_target_lua5-4 )