The docker-in-docker image now enables TLS by default (added in docker-library/docker#166), which complicates testing in our environment, and isn't needed for the tests we're running. This patch sets the `DOCKER_TLS_CERTDIR` to an empty value to disable TLS. Signed-off-by: Sebastiaan van Stijn <github@gone.nl> (cherry picked from commitb1a3c1aad1) Signed-off-by: Sebastiaan van Stijn <github@gone.nl> Upstream-commit:9c8ac0a123Component: cli