I've just tried it without "Version:" and with "Suite:" and "Codename:" set to jessie-backports.
After this, "apt-get update" prints the error (jessie expected but jessie- backports received): W: Konflikt bei Distribution: http://debian.jdesch.de jessie/ Release (jessie erwartet, aber jessie-backports bekommen) > ~~~~ > Origin: joede-backports > Label: Joedes Debian Jessie backports > Suite: stable > Version: 8.1 > Codename: jessie > NotAutomatic: yes > ButAutomaticUpgrades: yes > Architectures: amd64 > Components: main contrib > non-free Description: joede's local repository of backports > ~~~~~
