Running nixpkgs-update (https://nix-community.org/update-bot/) with UPDATE_INFO: colcon 0 -> 1
attrpath: colcon
Checking auto update branch...
[version] 
[version] skipping because derivation has updateScript
[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/wyzmm6s9w09ds8dnyxhr2dvfd3awg3w1-packages.json.drv
building '/nix/store/wyzmm6s9w09ds8dnyxhr2dvfd3awg3w1-packages.json.drv'...

Going to be running update for following packages:
 - colcon-core-0.19.0

Press Enter key to continue...
Running update for:
Enqueuing group of 1 packages
 - colcon-core-0.19.0: UPDATING ...
 - colcon-core-0.19.0: DONE.

Packages updated!

Diff after rewrites:
diff --git a/pkgs/development/python-modules/colcon/default.nix b/pkgs/development/python-modules/colcon/default.nix
index 8c53dc78bfed..3c9f67bdd93c 100644
--- a/pkgs/development/python-modules/colcon/default.nix
+++ b/pkgs/development/python-modules/colcon/default.nix
@@ -21,14 +21,14 @@
 
 buildPythonPackage rec {
   pname = "colcon-core";
-  version = "0.19.0";
+  version = "0.20.1";
   pyproject = true;
 
   src = fetchFromGitHub {
     owner = "colcon";
     repo = "colcon-core";
     tag = version;
-    hash = "sha256-R/TVHPT305PwaVSisP0TtbgjCFBwCZkXOAgkYhCKpyY=";
+    hash = "sha256-FV/G2FcnBgr7mUY/Jr+bVAdEfhHL9qAnpc92hpTfy7Y=";
   };
 
   build-system = [ setuptools ];

No auto update branch exists
There might already be an open PR for this update:
- python3Packages.colcon: 0.19.0 -> 0.20.1
  URL "https://api.github.com/repos/NixOS/nixpkgs/issues/497963"