klipper 0 -> 1
attrpath: klipper
Checking auto update branch...
[version] 
[version] skipping because derivation has updateScript
[rustCrateVersion] 
[rustCrateVersion] No cargoSha256 or cargoHash found
[golangModuleVersion] 
[golangModuleVersion] Not a buildGoModule package with vendorSha256 or vendorHash
[npmDepsVersion] 
[npmDepsVersion] No npmDepsHash
[updateScript] 
[updateScript] Success
[updateScript] this derivation will be built:
  /nix/store/iw5bbzd0lp81jhjl19ci229a1zvrx460-packages.json.drv
building '/nix/store/iw5bbzd0lp81jhjl19ci229a1zvrx460-packages.json.drv'...

Going to be running update for following packages:
 - klipper-unstable-2024-03-19

Press Enter key to continue...
Running update for:
 - klipper-unstable-2024-03-19: UPDATING ...
 - klipper-unstable-2024-03-19: DONE.

Packages updated!

Diff after rewrites:
diff --git a/pkgs/servers/klipper/default.nix b/pkgs/servers/klipper/default.nix
index b2067020ad9f..8269ed7355e3 100644
--- a/pkgs/servers/klipper/default.nix
+++ b/pkgs/servers/klipper/default.nix
@@ -8,13 +8,13 @@
 
 stdenv.mkDerivation rec {
   pname = "klipper";
-  version = "unstable-2024-03-19";
+  version = "unstable-2024-03-21";
 
   src = fetchFromGitHub {
     owner = "KevinOConnor";
     repo = "klipper";
-    rev = "235b75be3c287a9fdcde54b347734bf6a8de2ade";
-    sha256 = "sha256-PTdLhoKTlvrTljAvrK8q/JF9w50kKJHkWrzdPPaSfCc=";
+    rev = "d9043345b615a4b64333a006d9f1fd40f386a5e4";
+    sha256 = "sha256-AnFEHBWk6NVRowb0XWUFMmm6263XRr8L/ezgF8zaemQ=";
   };
 
   sourceRoot = "${src.name}/klippy";

No auto update branch exists
There might already be an open PR for this update:
- moonraker: unstable-2023-12-16 -> unstable-2024-01-21
  URL "https://api.github.com/repos/NixOS/nixpkgs/issues/202276"