Fix the race condition in Configuration updates (#722)
Fix the race condition in Configuration updates (#722)

Fixes #710

This fixes the irreconcilable state issue due to a race condition
in configuration updates from route controller and configuration
controller. If route controller succeeds in updating the configuration
first, it gets into a state where revision is created but configuration
status is not updated. This causes the synchandler to return error each
time when it is called.
knative/serving,knative/serving