Remove race condition in sync e2e test

test/e2e/12_sync.bats

@@ -50,12 +50,10 @@ function setup() {
   poll_until_true 'workload podinfo' 'kubectl -n demo describe deployment/podinfo'
 
   # Check the sync tag
-  git pull -f --tags
-  local sync_tag_hash
-  sync_tag_hash=$(git rev-list -n 1 flux)
   local head_hash
   head_hash=$(git rev-list -n 1 HEAD)
-  [ "$head_hash" = "$sync_tag_hash" ]
+  poll_until_equals "sync tag" "$head_hash" 'git pull -f --tags > /dev/null 2>&1; git rev-list -n 1 flux'
+
   podinfo_image=$(kubectl get pod -n demo -l app=podinfo -o"jsonpath={['items'][0]['spec']['containers'][0]['image']}")
 
   # Bump the image of podinfo, duplicate the resource definition (to cause a sync failure)