How do I force Kubernetes to re-pull an image?

I have the following replication controller in Kubernetes on GKE:

apiVersion: v1
kind: ReplicationController
metadata:
  name: myapp
  labels:
    app: myapp
spec:
  replicas: 2
  selector:
    app: myapp
    deployment: initial
  template:
    metadata:
      labels:
        app: myapp
        deployment: initial
    spec:
      containers:
      - name: myapp
        image: myregistry.com/myapp:5c3dda6b
        ports:
        - containerPort: 80
      imagePullPolicy: Always
      imagePullSecrets:
        - name: myregistry.com-registry-key

Now, if I say

kubectl rolling-update myapp --image=us.gcr.io/project-107012/myapp:5c3dda6b

the rolling update is performed, but no re-pull. Why?

One has to group imagePullPolicy inside the container data instead of inside the spec data. However, I filed an issue about this because I find it odd. Besides, there is no error message.

So, this spec snippet works:

spec:
  containers:
  - name: myapp
    image: myregistry.com/myapp:5c3dda6b
    ports:
    - containerPort: 80
    imagePullPolicy: Always
  imagePullSecrets:
    - name: myregistry.com-registry-key

Please be aware, that if the image is already cached on the local node, it will not be re-pulled (you will have to change the remote image). This applies even when the local image is actually different, e.g. corrupted by misguided attempts to free some space manually, because image checksums are not re-computed.