Add explanation and clean up MockFailedComputeOnOldHost class
Add explanation and clean up MockFailedComputeOnOldHost class

OpenSourcePolicyCenter/webapp-public,OpenSourcePolicyCenter/webapp-public,OpenSourcePolicyCenter/PolicyBrain,OpenSourcePolicyCenter/PolicyBrain,OpenSourcePolicyCenter/webapp-public,OpenSourcePolicyCenter/PolicyBrain,OpenSourcePolicyCenter/webapp-public,OpenSourcePolicyCenter/PolicyBrain