Fix nix installer up

installers/install-nix.sh

@@ -9,6 +9,10 @@ set -x
 # Abort installation if Nix is already installed
 if [ -d /nix/store ]; then
   exit 0
+elif ! [ -O /nix ]; then
+  # If we don't own /nix use sudo to chown it.
+  # If we can't sudo then nothing we do here will work so we just let this fail
+  sudo chown $UID /nix
 fi
 
 # Workaround to make a single user install work as root