Retroactively filing https://github.com/jenkinsci/jenkins/commit/ea85489a0a8eafaf70917af8079a1839b264c1e7 for LTS backport consideration from 1.535. Makes it awkward to write JenkinsRule tests for plugins which depend on plugins (like cloudbees-folder) with optional dependencies: you have to include the whole dependency tree in your POM.

(The corresponding fix for HudsonTestCase was in 1.501.)