With the switch to branches, it is likely that developers will try the following, which was formerly how to do a backport to the current stabilization release, when it was in a separate repo:

/backport jdk23

This lists a not-very-helpful error message that will point the developer to jdk23u. This is not the right thing if you really do want it backported to jdk23.

I suggest two changes to make the error message more helpful:

1. In response to "/backport jdk23", print a message asking if they meant ":jdk23" for the stabilization branch.
2. In addition to listing all of the possible repos that can be targeted with `/backport`, indicate that the jdk repo has an active jdk23 branch that can be targeted.

At least the first one should be easy enough to implement. The second might need a little thought, since we only want to list active branches during stabilization (and not old branches for releases that have already shipped).