Diagnosis of an NPE probably caused by a transient slave connection error.

java.lang.NullPointerException
	at hudson.tasks.CommandInterpreter.createScriptFile(CommandInterpreter.java:104)
	at hudson.tasks.CommandInterpreter.perform(CommandInterpreter.java:66)
	at hudson.tasks.CommandInterpreter.perform(CommandInterpreter.java:58)
	at com.cloudbees.hudson.plugins.modeling.impl.builder.BuilderImpl.perform(BuilderImpl.java:58)
	at hudson.plugins.m2extrasteps.M2ExtraStepsWrapper.executeBuildSteps(M2ExtraStepsWrapper.java:166)
	at hudson.plugins.m2extrasteps.M2ExtraStepsWrapper.access$200(M2ExtraStepsWrapper.java:43)
	at hudson.plugins.m2extrasteps.M2ExtraStepsWrapper$1.tearDown(M2ExtraStepsWrapper.java:137)
	at hudson.maven.MavenModuleSetBuild$RunnerImpl.doRun(MavenModuleSetBuild.java:817)
	at hudson.model.AbstractBuild$AbstractRunner.run(AbstractBuild.java:490)
	at hudson.model.Run.run(Run.java:1442)
	at hudson.maven.MavenModuleSetBuild.run(MavenModuleSetBuild.java:477)
	at hudson.model.ResourceController.execute(ResourceController.java:88)
	at hudson.model.Executor.run(Executor.java:239)