title: chart metadata (Chart.yaml) missing on helm upgrade
body: <p>I was following this <a href="https://towardsdatascience.com/kubernetesexecutor-for-airflow-e2155e0f909c" rel="noreferrer">blog post</a> and at this command, </p>
  
  <p><code>helm upgrade --install airflow airflow/ \
      --namespace airflow \
      --values values.yaml</code></p>
  
  <p>I got this error. 
  <code>in airflow: chart metadata (Chart.yaml) missing</code> but I actually have the Chart.yaml file under <code>airflow/</code>. </p>
  
  <pre class="lang-sh prettyprint-override"><code>$ ls
  Chart.yaml      charts          requirements.yaml   tiller.yaml
  Icon?           requirements.lock   templates       values.yaml
  </code></pre>
  
  <p>helm version &amp; kubectl pod below</p>
  
  <pre><code>$ helm version
  Client: &amp;version.Version{SemVer:"v2.13.1", GitCommit:"618447cbf203d147601b4b9bd7f8c37a5d39fbb4", GitTreeState:"clean"}
  Server: &amp;version.Version{SemVer:"v2.13.1", GitCommit:"618447cbf203d147601b4b9bd7f8c37a5d39fbb4", GitTreeState:"clean"}
  </code></pre>
  
  <pre><code>$ kubectl get pods --namespace kube-system
  NAME                                    READY     STATUS    RESTARTS   AGE
  coredns-fb8b8dccf-9z8v5                 1/1       Running   3          6h
  coredns-fb8b8dccf-wdtpl                 1/1       Running   3          6h
  etcd-minikube                           1/1       Running   1          6h
  kube-addon-manager-minikube             1/1       Running   1          6h
  kube-apiserver-minikube                 1/1       Running   1          6h
  kube-controller-manager-minikube        1/1       Running   1          6h
  kube-proxy-m4whq                        1/1       Running   0          2h
  kube-scheduler-minikube                 1/1       Running   1          6h
  kubernetes-dashboard-79dd6bfc48-5z9cx   1/1       Running   3          6h
  storage-provisioner                     1/1       Running   3          6h
  tiller-deploy-8458f6c667-wmv62          1/1       Running   1          4h
  </code></pre>
  
  <p>Could someone help to fix it?</p>