Add the '--force-upgrade' flag to 'helm init' to allow auto-downgrade

Signed-off-by: Rémy Coutable <remy@rymai.me>

doc/development/testing_guide/review_apps.md

@@ -129,6 +129,10 @@ two node pools:
 
 ### Helm/Tiller
 
+The Helm/Tiller version used is defined in the
+[`registry.gitlab.com/gitlab-org/gitlab-build-images:gitlab-charts-build-base` image](https://gitlab.com/gitlab-org/gitlab-build-images/blob/master/Dockerfile.gitlab-charts-build-base#L4)
+used by the `review-deploy` and `review-stop` jobs.
+
 The `tiller` deployment (the Helm server) is deployed to a dedicated node pool
 that has the `app=helm` label and a specific
 [taint](https://kubernetes.io/docs/concepts/configuration/taint-and-toleration/)

scripts/review_apps/review-apps.sh

@@ -126,6 +126,7 @@ function install_tiller() {
   helm init \
     --wait \
     --upgrade \
+    --force-upgrade \
     --node-selectors "app=helm" \
     --replicas 3 \
     --override "spec.template.spec.tolerations[0].key"="dedicated" \