I have the "refspec" empty so git plugin fetches all remote branches as documented. We are only interested in building origin/master (but we need the other branches around for the build).
I am trying to put in the branch settings things like "refs/remotes/origin/master" or just "origin/master" but whatever I type in is ignored and some other remote branch gets built. It seems like whatever gets typed in in that input box has no effect whatsoever. Even if I type a reference that does not exists like "ref/foo/bar", it will (a) not give an error, and (b) check the same random branch. Here is a console output that demonstrates:
Notice the "refs/foo/bar" at the end? It always checkouts the same commit, no matter what branch I give it.