Fix virtualbox presence check

build_vagrant_only.sh

@@ -30,9 +30,9 @@ check_vagrant() {
 # Returns 0 if not installed or 1 if installed
 check_virtualbox_installed() {
   if ! which VBoxManage >/dev/null; then
-    echo "1"
-  else
     echo "0"
+  else
+    echo "1"
   fi
 }