Revision gets active before replicas are ready

[johnugeorge]

In what area(s)?

/area API

What version of Knative?

v1.13

Expected Behavior

Revision should be ready only when all replicas are up

Actual Behavior

Revision is ready before all replicas are up

Steps to Reproduce the Problem

The cluster has resources only for 8 replicas for the knative service.

1. Create a knative service with replica=4
   Observation: Revision is ready with all 4 running replica
2. Delete the service
   Observation: Service is deleted and pods are getting terminated
3. Create the same service(same name) with replica=10 immediately during the pod termination time(Note: Cluster doesn't have enough resources for 10 replicas)
   Revision becomes ready immediately when 1 replica is running.
   Knative service also becomes ready
   Here is the transitions that I observed

Initially

kubectl get revision

NAME                                  CONFIG NAME                     K8S SERVICE NAME   GENERATION   READY   REASON   ACTUAL REPLICAS   DESIRED REPLICAS

example-predictor-00001         example-predictor                                             1          True             1                 10

After some time,

k get revision

NAME                                  CONFIG NAME                     K8S SERVICE NAME   GENERATION   READY   REASON   ACTUAL REPLICAS   DESIRED REPLICAS

example-predictor-00001          example-predictor                                          1          True             8                 10
```

Note: The state doesn't recover once the problem has occured. Ready is always true but active status is Unknown.  
  
4. If I redo the same step 3 after pods are terminated,  revision active status and ready status is Unknown. Knative service is also unknown. 

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