Add refspec to docker-publish job

Change-Id: Ie6cff3d4e5b042416582337e9216a2eb4e8d0c9b
diff --git a/jjb/pipeline/docker-publish.groovy b/jjb/pipeline/docker-publish.groovy
index 9738c62..d0c0e13 100644
--- a/jjb/pipeline/docker-publish.groovy
+++ b/jjb/pipeline/docker-publish.groovy
@@ -25,7 +25,7 @@
       steps {
         checkout([
           $class: 'GitSCM',
-          userRemoteConfigs: [[ url: "${params.gitUrl}", credentialsId: 'onos-jenkins-ssh']],
+          userRemoteConfigs: [[ url: "${params.gitUrl}", credentialsId: 'onos-jenkins-ssh', refspec: "${params.gitRefSpec}"]],
           branches: [[ name: "${params.gitRef}", ]],
           extensions: [
             [$class: 'WipeWorkspace'],