The development of inheritance plugin looks like it's dead.

I think this plugin should be marked with adopt-this-plugin plugin, see: https://wiki.jenkins-ci.org/display/JENKINS/Adopt+a+Plugin

Secondly I think the GitHub repository is redundant (https://github.com/i-m-c/jenkins-inheritance-plugin) and I think it should be forked into jenkinsci/, where other plugins are, so it's possible for somebody to adopt this plugin.