nix/devices: fix order in rebuild script

nix/os/devices/default.nix

@@ -26,6 +26,10 @@ let
 
     [[ -e "''${NIXOS_CONFIG}" ]]
 
+    if test -L result; then
+      rm result
+    fi
+
     ${if (builtins.elem rebuildarg rebuildargsSudo)
           && (builtins.match ".*--target-host.*" moreargs) == null
       then
@@ -33,10 +37,6 @@ let
       else
         ""
     }
-
-    if test -L result; then
-      rm result
-    fi
     nixos-rebuild --show-trace -I nixos-config=''${NIXOS_CONFIG} ${rebuildarg} ${moreargs}
   '';