s/rpmbuild/rpm-build 
s/rpmbuild/rpm-build 

When I followed these instructions, the generated path was 'rpm-build', not 'rpmbuild'. My rpm-build version is rpm-build-4.11.1-25.el7.x86_64 if that's relevant. Maybe this is 'just me', but wanted to feed back in case it's the same for everyone.
thaim/ansible,thaim/ansible