The %install stage contains the command
: make -j$numprocs check || :
$numprocs is not defined there (only in the %build-stage). So make will be
: make -j check
and won't limit number of processes. Although such a call is a good
hardware check, it is unsuitably for building rpms ;)
I recommend to define $numprocs like in the %build stage.
This is a feature - users are supposed things we've compiled, not stuff
they've broken themselves. ;)
Fixed in 3.4-8.