expose the display name of the build as environment variable

core/src/main/java/jenkins/model/CoreEnvironmentContributor.java

@@ -29,6 +29,8 @@ public class CoreEnvironmentContributor extends EnvironmentContributor {
             env.putAll(compEnv);
         }
 
+        env.put("BUILD_DISPLAY_NAME",r.getDisplayName());
+
         Jenkins j = Jenkins.getInstance();
         String rootUrl = j.getRootUrl();
         if(rootUrl!=null) {

core/src/main/resources/jenkins/model/CoreEnvironmentContributor/buildEnv.groovy

@@ -3,7 +3,7 @@ package jenkins.model.CoreEnvironmentContributor;
 def l = namespace(lib.JenkinsTagLib)
 
 // also advertises those contributed by Run.getCharacteristicEnvVars()
-["BUILD_NUMBER","BUILD_ID","JOB_NAME","BUILD_TAG","EXECUTOR_NUMBER","NODE_NAME","NODE_LABELS","WORKSPACE","JENKINS_HOME","JENKINS_URL","BUILD_URL","JOB_URL"].each { name ->
+["BUILD_NUMBER","BUILD_ID","BUILD_DISPLAY_NAME","JOB_NAME","BUILD_TAG","EXECUTOR_NUMBER","NODE_NAME","NODE_LABELS","WORKSPACE","JENKINS_HOME","JENKINS_URL","BUILD_URL","JOB_URL"].each { name ->
     l.buildEnvVar(name:name) {
         raw(_("${name}.blurb"))
     }

core/src/main/resources/jenkins/model/CoreEnvironmentContributor/buildEnv.properties

 BUILD_NUMBER.blurb=The current build number, such as "153"
 BUILD_ID.blurb=The current build id, such as "2005-08-22_23-59-59" (YYYY-MM-DD_hh-mm-ss)
+BUILD_DISPLAY_NAME.blurb=The display name of the current build, which is something like "#153" by default.
 JOB_NAME.blurb=Name of the project of this build, such as "foo" or "foo/bar"
 BUILD_TAG.blurb=String of "jenkins-<i>$'{'JOB_NAME}</i>-<i>$'{'BUILD_NUMBER}</i>". Convenient to put into a resource file, a jar file, etc for easier identification.
 EXECUTOR_NUMBER.blurb=\