truvari 0 -> 1
attrpath: truvari
Checking auto update branch...
[version] 
[version] generic version rewriter does not support multiple hashes
[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/gjjm2k06bpswly0c5fvxdvcby1j9r2w8-packages.json.drv
building '/nix/store/gjjm2k06bpswly0c5fvxdvcby1j9r2w8-packages.json.drv'...

Going to be running update for following packages:
 - truvari-4.1.0

Press Enter key to continue...
Running update for:
 - truvari-4.1.0: UPDATING ...
 - truvari-4.1.0: DONE.

Packages updated!

Diff after rewrites:
diff --git a/pkgs/applications/science/biology/truvari/default.nix b/pkgs/applications/science/biology/truvari/default.nix
index 946f4be60632..eaa314cc46a4 100644
--- a/pkgs/applications/science/biology/truvari/default.nix
+++ b/pkgs/applications/science/biology/truvari/default.nix
@@ -10,19 +10,19 @@ let
   ssshtest = fetchFromGitHub {
     owner = "ryanlayer";
     repo = "ssshtest";
-    rev = "d21f7f928a167fca6e2eb31616673444d15e6fd0";
+    rev = "refs/tags/v${version}";
     hash = "sha256-zecZHEnfhDtT44VMbHLHOhRtNsIMWeaBASupVXtmrks=";
   };
 in python3Packages.buildPythonApplication rec {
   pname = "truvari";
-  version = "4.1.0";
+  version = "4.2.0";
   pyproject = true;
 
   src = fetchFromGitHub {
     owner = "ACEnglish";
     repo = "truvari";
     rev = "v${version}";
-    hash = "sha256-HFVAv1TTL/nMjr62tQKhMdwh25P/y4nBGzSbxoJxMmo=";
+    hash = "sha256-3KL1sfSVzG5wewyhBvMWzx7/unIVPa/jF1ChGyOI6KM=";
   };
 
   postPatch = ''

The derivation has no 'version' attribute, so do not know how to figure out the version while doing an updateScript update