use bash for compile step execution

Change-Id: I1422d816d22cd1604f4cd6a26e32a2f5732b4fbd
diff --git a/Jenkinsfile b/Jenkinsfile
index ae70b26..de85c49 100644
--- a/Jenkinsfile
+++ b/Jenkinsfile
@@ -4,7 +4,7 @@
     stages {
         stage('build') {
             steps {
-                sh '. tools/build/envDefaults && onos-buck build onos'
+                bash '. tools/build/envDefaults && onos-buck build onos'
             }
         }
     }