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

Calculating dependencies ... done!
Dependency resolution took 0.82 s (backtrack: 0/20).


!!! All ebuilds that could satisfy "=sci-mathematics/gimps-30.8.17" have been masked.
!!! One of the following masked packages is required to complete your request:
- sci-mathematics/gimps-30.8.17::gentoo (masked by: GIMPS license(s))
A copy of the 'GIMPS' license is located at '/Volumes/Disk 1/Repository/portage-git/licenses/GIMPS'.


For more information, see the MASKED PACKAGES section in the emerge
man page or refer to the Gentoo Handbook.