Automatic merge from submit-queue
Attempt 2: Bump GCE containerVM to container-v1-3-v20160517 (Docker 1.11.1) again.
Workaround the issue of small root_maxkeys on the debian based container-vm image, and bump our image to the new alpha version for docker 1.11.1 validation.
ref: #23397#25893
cc/ @vishh @timstclair