Exit if update can't see free disk space

wemd

@@ -330,6 +330,7 @@ update() {
     if ! [[ "${__free_space}" =~ $re ]] ; then
         echo "Unable to determine free disk space. This is likely a bug."
         echo "df reports $(df -P "$(pwd)") and __free_space is ${__free_space}"
+        exit 130
     elif [ "$(df -P "$(pwd)" | awk '/[0-9]%/{print $(NF-2)}')" -lt 1024 ]; then
         echo "You have less than 1 MiB of space left on $(pwd)."
         echo "Aborting, as an update is not safe."