CORD-1019 Repeat 'vagrant destroy' if it fails

Change-Id: I9b690ecd3a523244b3e9cb2c8010ed6398a982fc
diff --git a/scripts/cord-in-a-box.sh b/scripts/cord-in-a-box.sh
index 583f235..35415f7 100755
--- a/scripts/cord-in-a-box.sh
+++ b/scripts/cord-in-a-box.sh
@@ -40,7 +40,7 @@
   then
     echo "Destroying all Vagrant VMs"
     cd $CORDDIR/build
-    sudo su $USER -c 'vagrant destroy'
+    for i in `seq 12`; do sudo su $USER -c 'vagrant destroy' && break; done
   fi
 
   echo "Removing $CORDDIR"