Only do nfs mount on build* machines

tasks/koji/base_builder.yml

@@ -141,7 +141,7 @@
 
 - name: nfs mount points
   action: mount name=/mnt/koji src=nfs01.phx2.fedoraproject.org:/ fstype=nfs4 opts=ro,hard,bg,intr,noatime,nodev,nosuid passno=0 dump=0 state=mounted
-  only_if: "not '${inventory_hostname}'.startswith('bkernel')"
+  only_if: "'${inventory_hostname}'.startswith('build')"
 
 # mock configs for pungify job
 - name: put extra special  mock configs in