This build passes locally.

cmake/build_moose-core.sh.in

@@ -6,9 +6,8 @@ set -e
 # NOTICE: This file is parsed by cmake to create a shell script. Not all syntax
 # will play well with cmake. CMAKE replaces @FOO@ and ${FOO} with cmake variable
 # values.
-NPROC=$(nproc)
 if [ -z $MAKEOPTS ]; then
-    export MAKEOPTS="-j${NPROC}"
+    export MAKEOPTS="-j`nproc`"
 fi
 
 echo "Building pymoose and creating bdist."