The settings for a job using postbuildscript plugin 1.1.0 are not persistent.

1. Run the attached DSL job, this will create a job called 'foobar'
2. Examine the resulting config.xml (do not edit using Jenkins, yet).
3. The postbuildscript shell task in config.xml should look like so:

<publishers>
<org.jenkinsci.plugins.postbuildscript.PostBuildScript plugin="postbuildscript@1.1.0">
<config>
<genericScriptFiles/>
<groovyScriptFiles/>
<groovyScripts/>
<buildSteps>
<org.jenkinsci.plugins.postbuildscript.model.PostBuildStep>
<results>
<string>SUCCSESS</string>
<string>FAILURE</string>
<string>UNSTABLE</string>
</results>
<role>SLAVE</role>
<buildSteps>
<hudson.tasks.Shell>
<command>echo hello</command>
</hudson.tasks.Shell>
</buildSteps>
</org.jenkinsci.plugins.postbuildscript.model.PostBuildStep>
</buildSteps>
<markBuildUnstable>false</markBuildUnstable>
</config>
</org.jenkinsci.plugins.postbuildscript.PostBuildScript>
</publishers>

4. Configure the resulting job (foobar) using Jenkins, but don't save it
5. Re-examine config.xml for job "foobar", it should look like so:

<publishers>
<org.jenkinsci.plugins.postbuildscript.PostBuildScript plugin="postbuildscript@1.1.0">
<config>
<genericScriptFiles/>
<groovyScriptFiles/>
<groovyScripts/>
<buildSteps>
<org.jenkinsci.plugins.postbuildscript.model.PostBuildStep>
<results/>
<role>BOTH</role>
<buildSteps/>
</org.jenkinsci.plugins.postbuildscript.model.PostBuildStep>
</buildSteps>
<markBuildUnstable>false</markBuildUnstable>
</config>
</org.jenkinsci.plugins.postbuildscript.PostBuildScript>
</publishers>

The configuration has changed..