jenkinsci/join-plugin — pull request #7 by cesarwong (2014-02-12 03:30:08+00:00)
Title: Fix for Jenkins #16201

https://issues.jenkins-ci.org/browse/JENKINS-16201
In some cases, Jenkins will swap out the action map for a build. For the Join plugin, it means that information about completed tasks is lost when it's re-read from disk. Saving the parent build ensures that the current state of the join action.