The STABLE distro tag is hardcoded in two places: * default tag filter in reserve workflow * default tag filter in bkr workflow commands, unless a distro name was specified (and for bug 876752 this latter is carried over into machine-test as well, to stop it from breaking.) But STABLE is an (essentially undocumented) RHTS-ism. A while ago (0.9 I think) the code for tagging distros as STABLE was moved into the public source (LabController/addDistro/addDistro.d/updateDistro) but it's still not enabled by default. At the very least we need to add something to the installation docs pointing out that one lab controller must have add_distro=1 in /etc/sysconfig/beaker_lab_import so that the STABLE tags are set. Without them the reserve workflow and bkr workflow commands will not work properly. Another possibility is to remove the requirement for STABLE tagging entirely, for sites which don't care or don't want to bother. This might mean cleaning up the bkr workflow code to have a configurable default tag instead of hardcoding STABLE.
So the STABLE tagging stuff has been documented for a while now: https://beaker-project.org/docs/admin-guide/distro-import.html#automated-jobs-for-new-distros but we're no longer using it internally and it's not clear that it is useful to anyone else either. Also reserve workflow no longer defaults to STABLE (bug 1009583). So I think the right solution here is just to remove it from the default distro filter criteria in the bkr workflow commands as well. Users can pass --tag=STABLE explicitly if their site is actually using STABLE and they care about it.
http://gerrit.beaker-project.org/3363
Beaker 19.0 has been released.