diff deploy/linux/docker/Dockerfile_v3.0_ubuntu1604 @ 2152:60d78294ea3a

Oookay... Travis's Trusty image is now too old for the bundled hg to be able to connect to Bitbucket after the latter switched off TLS 1.0 and 1.1 support this month. So we must either use a newer image, or find another workaround. Let's try the newer image first, since we'd probably be using that already if it had existed when we set this up