I setup a matrix job with setup to build with many jdk's and only one node axis - the master node. We have two nodes, the master and a build node for special builds (documentation). But when i start the matrix build, it starts the build on the special build node - not on master.
The "special" build node on that the build is starts, is a node that i have restricted to "reserve for exclusive jobs". In my opinion it should no use such type of nodes.