Always answer empty list if deployments not ready

An empty deployments will cause json decode exception, and once
deployments=[] coming, it will trigger another refresh. Always answer
empty list when deployments not ready will solve above two issues.

Change-Id: Iaee3a3ef25cf9907aaefd941dcb316ecb25a29d6
Closes-Bug: #1298417
Merge "Always answer empty list if deployments not ready"