When I look at
$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=14.10
DISTRIB_CODENAME=utopic
DISTRIB_DESCRIPTION="Ubuntu 14.10"
But my /etc/apt/sources.list is already all vivid (15.04).
Running do-release-upgrade does start the process but says there are 0 packages to be upgraded.
How do I fully update my system to vivid?