Updating individual jira issues should not fail the build but rather log a warning message and continue

We are using jira-plugin as a post build step to mark all the relevant issues with the release version. However, if some of the issues had been marked as closed, the pluging logs a nasty message saying that the issue can not be updated (because it is closed) and fails the build. 
The proposed changes deal with this problem by logging a warning message if a particular issue can not be updated and continue marking other issues.