openshift-apps/coreos-koji-tagger: change bc source for staging

Allows us to test potential changes before merging them which will
trigger a build in prod and immediately start running in prod.

roles/openshift-apps/coreos-koji-tagger/templates/buildconfig.yml

@@ -9,8 +9,13 @@ spec:
     type: Git
     contextDir: coreos-koji-tagger
     git:
+{% if env == "staging" %}
       ref: master 
       uri: https://github.com/coreos/fedora-coreos-releng-automation.git
+{% else %}
+      ref: fedora-infra-staging
+      uri: https://github.com/coreos/fedora-coreos-releng-automation.git
+{% endif %}
   strategy:
     type: Docker
     dockerStrategy: