jenkinsci/matrix-project-plugin — pull request #9 by JeremyMarshall (2014-10-27 19:52:39+00:00)
Title: Fix NullPointerException if swapping between MatrixExecutionStrategies

I put together an execution strategy which uses a groovy script or groovy file but swapping between the default and mine caused a NPE due to the instance field not being populated after the switch, this fixes it by checking if the instance is there before using the attributes.