Verify that the xwiki-commons's top level POM has a xwiki.clirr.previous.version property correctly pointing to the latest release (for that branch) and if not, change it and ensure that all the CLIRR excludes are correct and remove those that are no longer valid.
Since the release is performed on agent-1, mark it offline in the Jenkins admin screen. Put as comment Temporarily marking agent-1 offline for the release of 4.2-milestone-1.