Describe the bug
Pilot is periodically pushing the xDS configuration to Envoy even there is no change, causing established TCP connections in Envoy broken.

Client side gets a lot of " unexpected end of stream on Connection".

Example: java.io.IOException: unexpected end of stream on Connection{172.168.40.61:12282, proxy=DIRECT hostAddress=/172.168.40.61:12282 cipherSuite=none protocol=http/1.1}

Expected behavior

• Pilot shouldn't push xDS configuration to Envoy if no changes
• Established downstream connections shouldn't be destroyed by Envoy unless the upstream service closes the connection itself.

Steps to reproduce the bug
No special steps to reproduce the bug, just run the application with istio and check the application log.

Version
Istio 1.0.0

Installation
Microservices are deployed and managed by Kubernetes, but use Consul as the service registry

Environment
Ubuntu 16.04

Cluster state
Microservices are deployed and managed by Kubernetes, but use Consul as the service registry