Related to #269, when a Promise is updated or the Promise pipeline is manually triggered, things in the system may change as a result of this. In #269 , it was the destination selectors. If we allow resource requests to be reconciled while this change occurring we might get odd behaviour, such as:

Promise:
  spec:
    destinationSelectors:
    - env: dev
   workflows:
     resource.configure.image: v0.1.0

Updated to:

Promise:
  spec:
    destinationSelectors:
    - env: **prod**
   workflows:
     resource.configure.image: **v0.2.0**

We could potentially end up running a resource request pipelines with image v0.2.0 and destination selectors env: dev, which is bad. Eventually the resource request would rerun with v0.2.0 and env: prod, but being this in-between state is potentially dangerous.