With matrix (multiconfiguration) build jobs one can select (groups of) slaves to build the job on with the axes. It would be nice if when an axis matches multiple nodes (i.e. a label that applies to more than one node, such as x86_64) the node list could be further filtered by (not) matching more labels.
For example, say I have a list of nodes with the following labels:
builder1: el5 x86_64
builder2: el5 i686
builder3: el5 x86_64 lab
builder4: el5 i686 lab
If one of my axis specifications is "el5" then any one of the above nodes would be selected as a slave to build on. However, what would be nice is to have a further filter on the selected nodes, like "lab", so that even though the axis specification of "el5" would match any of the available 4 nodes, that additional "lab" filter would mean that only builder3 and builder4 are eligible nodes.