null build slaves when selecting labels to build in matrix plugin

[Adam Mercer]

Hi

I've upgraded my test Jenkins instance to 1.580.1, to validate before
upgrading my production instance, and since doing so the matrix plugin
doesn't seem to be working correctly. When selecting nodes/labels to
build in the Configuration Matrix there doesn't seem to be any match
between label and nodes.

With 1.565.3 when selecting a label in brackets there was a list of
the nodes which satisfies this label, with 1.580.1 there is just
"null". Similarly when selecting nodes 1.565.3 shows the description
of the node whereas 1.580.1 shows "null".

Whilst this just seems to be a cosmetic issue I'm concerned that
because of this jobs could be run on machines without the appropriate
label and lead to unusual build errors.

Cheers

Adam

[Matt]

I have seen the same issue in 1.596.1 (LTS release). The jobs run correctly,
as before the upgrade, but the labels' member node lists in the
Configuration Matrix Label/Node section have been replaced by "null".