sane-private-unlock: fix perms

pkgs/by-name/sane-scripts/src/sane-private-unlock

@@ -1,6 +1,8 @@
 #!/usr/bin/env nix-shell
 #!nix-shell -i bash -p bash -p coreutils -p systemdMinimal
 
+umask 027
+
 if ! systemctl is-active private-storage.target > /dev/null; then
   echo "unable to access encrypted data store."
   echo "unlock it now or cancel with Ctrl+C."
@@ -10,7 +12,7 @@ while ! systemctl is-active private-storage.target > /dev/null; do
   # see: <https://stackoverflow.com/a/2654096>
   IFS= read -s -r -p "password: " line
   echo
-  if [[ "$?" -eq 0 ]]; then
+  if [[ "$?" -eq 0 && -n "$line" ]]; then
     echo -n "$line" > /run/gocryptfs/private.key
     # give time for the store to be unlocked
     timeout 3s systemctl start private-storage.target