[FIXED JENKINS-25164] Add JOB_BASE_NAME env var (#2321)

* [JENKINS-25164] Add SHORT_JOB_NAME env var

* Delete strip off

* [JENKINS-25164] Change SHORT_JOB_NAME for LEAF_JOB_NAME

* [JENKINS-25164] Change LEAF_JOB_NAME for JOB_BASE_NAME

core/src/main/java/hudson/model/Job.java

@@ -369,6 +369,7 @@ public abstract class Job<JobT extends Job<JobT, RunT>, RunT extends Run<JobT, R
         env.put("JENKINS_SERVER_COOKIE",SERVER_COOKIE.get());
         env.put("HUDSON_SERVER_COOKIE",SERVER_COOKIE.get()); // Legacy compatibility
         env.put("JOB_NAME",getFullName());
+        env.put("JOB_BASE_NAME", getName());
         return env;
     }
 

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","BUILD_DISPLAY_NAME","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", "JOB_BASE_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, identical to BUILD_NUMBER for builds created in 1.597+, but a YYYY-MM-DD_hh-mm-ss timestamp for older builds
 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". (To strip off folder paths from a Bourne shell script, try: <tt>$'{'JOB_NAME##*/}</tt>)
+JOB_NAME.blurb=Name of the project of this build, such as "foo" or "foo/bar".
+JOB_BASE_NAME.blurb=Short Name of the project of this build stripping off folder paths, such as "foo" for "bar/foo".
 BUILD_TAG.blurb=String of "jenkins-<i>$'{'JOB_NAME}</i>-<i>$'{'BUILD_NUMBER}</i>". Convenient to put into a resource file, a jar file, etc for easier identification.
 EXECUTOR_NUMBER.blurb=\
   The unique number that identifies the current executor \