explicitly use bash

Change-Id: I81b6560fbeb79aa51642650fe603fb03248ccb48
diff --git a/jjb/onos/onos-verify.yaml b/jjb/onos/onos-verify.yaml
index dee3eff..54f2be5 100644
--- a/jjb/onos/onos-verify.yaml
+++ b/jjb/onos/onos-verify.yaml
@@ -92,6 +92,7 @@
     builders:
     #put shell scripts in file then make sure shell check is installed on verify vms
       - shell: |
+            #!/bin/bash
             . tools/build/envDefaults
             echo $PATH
             onos-buck build onos