as the attached screen shot shows.
This overloads a build bot box.
Created attachment 524214 [details]
I'm unable to repro this issue locally and will be closing the ticket. Please reopen it if you experience this issue again.
I believe that in this case portage may have been invoked with MAKEOPTS=-j7?
> │ │ └─emake,31893 /usr/lib/portage/python2.7/ebuild-helpers/emake
> │ │ └─make,31906 -j7