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/jxr90cj61d8diqdg9nfva6rq77b83m0d-packages.json.drv
building '/nix/store/jxr90cj61d8diqdg9nfva6rq77b83m0d-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..b907f9347ed9 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="
-  },
   "x86_64-darwin": {
-    "buck2": "sha256-8SvAZ30ZFsamVAheKpa2vzGty1TZECUv+BHeXLlDneQ=",
-    "rust-project": "sha256-0af+q1s7iEb6dWl4WuNxFbIskTfrHtU2uhatPyAhZNM="
+    "buck2": "sha256-oTEly2jsgsUs4uu3YybPO28ywxwOYcV7fVfz/cGoxnQ=",
+    "rust-project": "sha256-hRdlQ7O4FcEHB6gDTv/EHmspeqA3K7O7NFIpbI8th90="
   },
-  "aarch64-linux": {
-    "buck2": "sha256-Pka0HEEqRsQp2R435duy6gJy/RQXp5lK5Dg9+rfr9L8=",
-    "rust-project": "sha256-u3b+XscQpNZOo8OTrLSazFZvm496U4nsWti/6TRf8ZA="
+  "x86_64-linux": {
+    "buck2": "sha256-NGODtuEj2udHn1en+ZdAt7C+vqRxMFA4D9bsMJ5B/F4=",
+    "rust-project": "sha256-peQLY2pgDIIGQqRGwie99kw4zm0O5yvs6ySA62DBS4Y="
   },
   "aarch64-darwin": {
-    "buck2": "sha256-1Fv0LzAZUN/BbcorCBaPBbm8JAzLarhJysLqPT78XEQ=",
-    "rust-project": "sha256-PQ7WKjzAPT0uRirWzwJPxKr9V1RQajnlXUMnv8SYdso="
+    "buck2": "sha256-4TycV0YF65aOVS/Wq15CGMVYkwe/viqceC+/tl3p9Wo=",
+    "rust-project": "sha256-2h+fxzq88Hl46HhoUL/TMULGNjLeDzKLtTFg61SLPA8="
+  },
+  "aarch64-linux": {
+    "buck2": "sha256-jZLZxUkO/ndhHI3rtnDFSNu5KINKJ7oLpLSYF9+8Lko=",
+    "rust-project": "sha256-ow72lmvWkvATNHu2TrBdutPGgIqYXgXrHIEQyGWjsog="
   },
-  "version": "2025-12-01",
-  "preludeGit": "0a994e0b600f7d035e1ac69f374c0e37e1e19af6",
-  "preludeFod": "sha256-IQa4VatN5OaDSyoTbAj1tHNBpJV6Ost9RbLxDD23xVQ="
+  "version": "2026-03-15",
+  "preludeGit": "27c8628d9bd9324e6dba3fd0e5c112e6ea4c5795",
+  "preludeFod": "sha256-PjCN1jcBmTUHMZjAXr4Zh9R8WFl+26xTt8H0VvnQ2vE="
 }

No auto update branch exists
There might already be an open PR for this update:
- buck2: unstable-2025-12-01 -> unstable-2026-03-15
  URL "https://api.github.com/repos/NixOS/nixpkgs/issues/501849"