use git to find commit author (#24240)

src/eo/Utils.groovy

@@ -15,12 +15,10 @@ def mail_notify(currentBuild, env, email) {
             recipients: email, sendToIndividuals: true
         ])
     } else {
+        author = sh(returnStdout: true, script: "/usr/bin/git show -s --format='%ae' HEAD").trim()
         step([
             $class: 'Mailer', notifyEveryUnstableBuild: true,
-            recipients: emailextrecipients([
-                [$class: 'CulpritsRecipientProvider'],
-                [$class: 'RequesterRecipientProvider']
-            ])
+            recipients: author, sendToIndividuals: true
         ])
     }
 }