JENKINS-27268 has been resolved but there are still many occurrences of the term "slave" in Jenkins core. Some of these are too hard to fix others are not, but it is unclear which are which.
We've put significant effort into removing this term. To make good on that investment, any public-facing stragglers, bugs need to be filed and linked for all remaining usages of "slave" in Jenkins core. Otherwise, the term will continue to be part of the project's vernacular.