Don't fail if build dir does not exist

Change-Id: I1613128e687d1f0b8c2868e0ab6d2f3cca833608
diff --git a/scripts/cord-in-a-box.sh b/scripts/cord-in-a-box.sh
index c37fb98..8c8435a 100755
--- a/scripts/cord-in-a-box.sh
+++ b/scripts/cord-in-a-box.sh
@@ -10,9 +10,12 @@
 function cleanup_from_previous_test() {
   echo "## Cleanup ##"
 
-  echo "Destroying all Vagrant VMs"
-  cd $CORDDIR/build
-  sudo su $USER -c 'vagrant destroy'
+  if [ -d $CORDDIR/build ]
+  then
+    echo "Destroying all Vagrant VMs"
+    cd $CORDDIR/build
+    sudo su $USER -c 'vagrant destroy'
+  fi
 
   echo "Removing $CORDDIR"
   cd ~