The demo installer fails to on jBPM eclipse because it doesn't point to the Final version. I changed to use the following and it worked:
<target name="download.jBPM.eclipse"
....
<get src="http://sourceforge.net/projects/jbpm/files/jBPM%205/jbpm-5.1.0.Final/jbpm-5.1.0.Final-eclipse-all.zip/download"