jenkinsci/jenkins — pull request #970 by vjuranek (2013-10-10 20:35:41+00:00)
Title: [FIXED JENKINS-19926] Add only new env. variables

Previous patch (3eea39648943583a530f47f69f93737266537d9d) broke usescases when evn. variable overwrites already existing one like PATH = $PATH:/my/path