I get NPE when adding JIRA Release version parameter and "Execute shell" build step and starting the job. Versions are picked up from Jira and can be selected when "Build with parameters clicked". Parameters sections in job results shows correct parameter value. Without "Execute shell" build is not failed. If I remove JIRA release version parameters - build is fine.
On windows environment everything is working fine.
JIRA plugin 2.1 does not have similar trouble.