Running nixpkgs-update (https://nix-community.org/update-bot/) with UPDATE_INFO: buck2 0 -> 1
attrpath: buck2
Checking auto update branch...
[version] 
[version] generic version rewriter does not support multiple hashes
[rustCrateVersion] 
[rustCrateVersion] No cargoHash found
[golangModuleVersion] 
[golangModuleVersion] Not a buildGoModule package with vendorHash
[npmDepsVersion] 
[npmDepsVersion] No npmDepsHash
[updateScript] 
[updateScript] Success
[updateScript] this derivation will be built:
  /nix/store/8f7c5j2icdyvc4fr8ys3nyv36gg0gqfm-packages.json.drv
building '/nix/store/8f7c5j2icdyvc4fr8ys3nyv36gg0gqfm-packages.json.drv'...

Going to be running update for following packages:
 - buck2-unstable-2025-12-01

Press Enter key to continue...
Running update for:
Enqueuing group of 1 packages
 - buck2-unstable-2025-12-01: UPDATING ...
 - buck2-unstable-2025-12-01: DONE.

Packages updated!

Diff after rewrites:
diff --git a/pkgs/by-name/bu/buck2/hashes.json b/pkgs/by-name/bu/buck2/hashes.json
index ced513105160..0654df431828 100644
--- a/pkgs/by-name/bu/buck2/hashes.json
+++ b/pkgs/by-name/bu/buck2/hashes.json
@@ -1,21 +1,21 @@
 {
   "x86_64-linux": {
-    "buck2": "sha256-TOgL0pLnNEAhHkKvynnM91kW06K6jZPeJnpSibYg8EU=",
-    "rust-project": "sha256-s5JY/m+yC3YNHiOxk6D43ZkWdtWLxlI4X72jSFFd3Hc="
+    "buck2": "sha256-E+KulIRHDtTnkTusrO3Q3LNWhEG8MxIkBAf4NKX7yFE=",
+    "rust-project": "sha256-MiGFvdY3pcruZu5M+k3s9Ym/e4eYjBJI0QlXtywAneA="
   },
   "x86_64-darwin": {
-    "buck2": "sha256-8SvAZ30ZFsamVAheKpa2vzGty1TZECUv+BHeXLlDneQ=",
-    "rust-project": "sha256-0af+q1s7iEb6dWl4WuNxFbIskTfrHtU2uhatPyAhZNM="
+    "buck2": "sha256-z3nmwaAjsflCLiygb7GoQfyVXflnHdItF4POF4eqWXE=",
+    "rust-project": "sha256-+yPeLbWIX49OjhoCgu+MVfw4DwUwi7LH/ZRZuYFksbg="
   },
   "aarch64-linux": {
-    "buck2": "sha256-Pka0HEEqRsQp2R435duy6gJy/RQXp5lK5Dg9+rfr9L8=",
-    "rust-project": "sha256-u3b+XscQpNZOo8OTrLSazFZvm496U4nsWti/6TRf8ZA="
+    "buck2": "sha256-u/oNBSkRBbGdQV3I/hFR5gVT2tCMP0tAyFWfhmge2YA=",
+    "rust-project": "sha256-x1GnRUQtVq4nHrZORPQyRHnCRY4ZRumnT8RYMR8rs9o="
   },
   "aarch64-darwin": {
-    "buck2": "sha256-1Fv0LzAZUN/BbcorCBaPBbm8JAzLarhJysLqPT78XEQ=",
-    "rust-project": "sha256-PQ7WKjzAPT0uRirWzwJPxKr9V1RQajnlXUMnv8SYdso="
+    "buck2": "sha256-ao4+az5w4ezzY+rPitAF5ZC+ZXGcYen1yECekZCRNr4=",
+    "rust-project": "sha256-AWwxh5Lws0J2ajXp4lMltII9K1CTHJnJx0TJUDZDrNE="
   },
-  "version": "2025-12-01",
-  "preludeGit": "0a994e0b600f7d035e1ac69f374c0e37e1e19af6",
-  "preludeFod": "sha256-IQa4VatN5OaDSyoTbAj1tHNBpJV6Ost9RbLxDD23xVQ="
+  "version": "2026-01-19",
+  "preludeGit": "860c936639d37361c925e2075b0369a6dd1feeb6",
+  "preludeFod": "sha256-Isd4PUfcICBDgLCdwitDzzT1lgySKzezl2Hb8Ps5O8c="
 }

No auto update branch exists
Old version unstable-2025-12-01" not present in master derivation file with contents: {
  "x86_64-linux": {
    "buck2": "sha256-TOgL0pLnNEAhHkKvynnM91kW06K6jZPeJnpSibYg8EU=",
    "rust-project": "sha256-s5JY/m+yC3YNHiOxk6D43ZkWdtWLxlI4X72jSFFd3Hc="
  },
  "x86_64-darwin": {
    "buck2": "sha256-8SvAZ30ZFsamVAheKpa2vzGty1TZECUv+BHeXLlDneQ=",
    "rust-project": "sha256-0af+q1s7iEb6dWl4WuNxFbIskTfrHtU2uhatPyAhZNM="
  },
  "aarch64-linux": {
    "buck2": "sha256-Pka0HEEqRsQp2R435duy6gJy/RQXp5lK5Dg9+rfr9L8=",
    "rust-project": "sha256-u3b+XscQpNZOo8OTrLSazFZvm496U4nsWti/6TRf8ZA="
  },
  "aarch64-darwin": {
    "buck2": "sha256-1Fv0LzAZUN/BbcorCBaPBbm8JAzLarhJysLqPT78XEQ=",
    "rust-project": "sha256-PQ7WKjzAPT0uRirWzwJPxKr9V1RQajnlXUMnv8SYdso="
  },
  "version": "2025-12-01",
  "preludeGit": "0a994e0b600f7d035e1ac69f374c0e37e1e19af6",
  "preludeFod": "sha256-IQa4VatN5OaDSyoTbAj1tHNBpJV6Ost9RbLxDD23xVQ="
}