I Apologize in advance if I've tagged the incorrect component(s). I'm not sure which is causing the explosion in the bug.

Environment is:
CentOS 6.4
Jenkins 1.526
Java 1.6.0_24

Aug 6, 2013 10:18:33 AM hudson.util.RobustReflectionConverter doUnmarshal
WARNING: Skipping a non-existent field executeOnMatrixNodes
com.thoughtworks.xstream.converters.reflection.MissingFieldException: No field 'executeOnMatrixNodes' found in class 'org.jenkinsci.plugins.postbuildscript.PostBuildScript'
at com.thoughtworks.xstream.converters.reflection.FieldDictionary.field(FieldDictionary.java:94)
at com.thoughtworks.xstream.converters.reflection.PureJavaReflectionProvider.getFieldType(PureJavaReflectionProvider.java:157)
at hudson.util.RobustReflectionConverter.determineType(RobustReflectionConverter.java:399)
at hudson.util.RobustReflectionConverter.doUnmarshal(RobustReflectionConverter.java:271)
at hudson.util.RobustReflectionConverter.unmarshal(RobustReflectionConverter.java:222)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:72)
at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:65)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:66)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:50)
at com.thoughtworks.xstream.converters.collections.AbstractCollectionConverter.readItem(AbstractCollectionConverter.java:71)
at hudson.util.CopyOnWriteList$ConverterImpl.unmarshal(CopyOnWriteList.java:193)
at hudson.util.DescribableList$ConverterImpl.unmarshal(DescribableList.java:263)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:72)
at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:65)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:66)
at hudson.util.RobustReflectionConverter.unmarshalField(RobustReflectionConverter.java:333)
at hudson.util.RobustReflectionConverter.doUnmarshal(RobustReflectionConverter.java:275)
at hudson.util.RobustReflectionConverter.unmarshal(RobustReflectionConverter.java:222)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:72)
at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:65)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:66)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:50)
at com.thoughtworks.xstream.core.TreeUnmarshaller.start(TreeUnmarshaller.java:134)
at com.thoughtworks.xstream.core.AbstractTreeMarshallingStrategy.unmarshal(AbstractTreeMarshallingStrategy.java:32)
at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:1061)
at hudson.util.XStream2.unmarshal(XStream2.java:109)
at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:1045)
at com.thoughtworks.xstream.XStream.fromXML(XStream.java:925)
at hudson.XmlFile.read(XmlFile.java:143)
at hudson.model.Items.load(Items.java:220)
at jenkins.model.Jenkins$18.run(Jenkins.java:2553)
at org.jvnet.hudson.reactor.TaskGraphBuilder$TaskImpl.run(TaskGraphBuilder.java:146)
at org.jvnet.hudson.reactor.Reactor.runTask(Reactor.java:259)
at jenkins.model.Jenkins$7.runTask(Jenkins.java:895)
at org.jvnet.hudson.reactor.Reactor$2.run(Reactor.java:187)
at org.jvnet.hudson.reactor.Reactor$Node.run(Reactor.java:94)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:679)