Jenkins Groovy script to inject the current build environment variables into current environment.

JenkinsInjectBuildEnvironment.groovy

// Use the following Groovy script to inject into the current build context
// Install the EnvInject plugin, https://wiki.jenkins.io/display/JENKINS/EnvInject+Plugin.
// In your job, Enable the Inject environment variables to the build process and
// Enter in the Evaluated Groovy script field. Make sure to keep the Use Groovy Sandbox
// unchecked. This script returns a hashmap of all environment variables including
// build specific ones into the current environment. 
//
// By doing this, Jenkins specific environment variables can be accessed later on
// in a non=system Groovy script with a simple way. For example, to get the value of the
// JENKINS_URL is done this way:
//
// def env = System.getenv()
// println env['JENKINS_URL']
//
def thr = Thread.currentThread()
def config =  new HashMap()
def build = thr?.executable
def env = build.parent.builds[0].properties.get("envVars")
config.putAll(env)
return config