fix typo...

Change-Id: Ica8ca00ec6e7c41cbaef44bce8c6e56c3637a229
diff --git a/jobs.yaml b/jobs.yaml
index dc005eb..d5a7c80 100644
--- a/jobs.yaml
+++ b/jobs.yaml
@@ -70,7 +70,7 @@
     builders:
       - shell: stdbuf -oL -eL mispipe "sudo ~mininet/mininet/util/vm/build.py -v --branch {branch} --test sanity {flavor} --chown `whoami`"  "tr '\r' ' '"
       - shell: zip `basename -s .ovf */*.ovf`.zip */*.vmdk */*.ovf
-      - shasum */*.vmdk */*.ovf */*.zip > `basename -s .ovf */*.ovf`.sha
+      - shell: shasum */*.vmdk */*.ovf */*.zip > `basename -s .ovf */*.ovf`.sha
     publishers:
       - archive:
             artifacts: '**'