I got this message error while I was trying to install JBPM5 "can't get http://hudson.jboss.org/hudson/job/drools/lastSuccessfulBuild/artifact/trunk/target/drools-5.2.0-SNAPSHOT-eclipse-all.zip" I've found that file into http://hudson.jboss.org/hudson/job/drools/lastSuccessfulBuild/artifact/target/drools-5.2.0-SNAPSHOT-eclipse-all.zip. I Downloaded it manually and I've put it under Lib folder.
Thanks, apparently the download url for drools has recently changed
You can easily change the url in the build.properties file and remove the trunk part though.
I committed that change for future versions.