Fix publishing infra/publications

The two publishing jobs failed, fix them:
* ZUUL_REFNAME in playbooks/publications/run.yaml#n12 is not set, use
  the proper variable.
* index publishing is done from master, always check out master for
  this like it was done for version 2.

Change-Id: I494c69e51282418bbc7cac45454abe8c52e6920f

playbooks/publications/run.yaml

@@ -9,7 +9,7 @@
         cmd: |
           set -x
           # NAME will either be the branch name or the tag name
-          NAME=`echo $ZUUL_REFNAME | sed 's/refs.tags.//'`
+          NAME=`echo {{ zuul.ref }} | sed 's/refs.tags.//'`
           mkdir -p _out/$NAME
           for FN in * ; do
               if [ "_out" != "$FN" ] ; then

zuul.d/jobs.yaml

@@ -496,6 +496,8 @@
     post-run:
       - playbooks/publish/publications-index.yaml
       - playbooks/publish/openstack-afs.yaml
+    # Index is always published from master
+    override-branch: master
     allowed-projects:
       - openstack-infra/publications
     roles: