chore: git rev-parse not reliable in github-runner

dev/flake.nix

@@ -39,19 +39,18 @@
           meta.description = program.meta.description;
           program = pkgs.writeShellApplication {
             name = "cz-check";
-            runtimeInputs = [ pkgs.git config.pre-commit.settings.tools.commitizen ];
+            runtimeInputs = with pkgs; [ config.pre-commit.settings.tools.commitizen git gnugrep coreutils ];
             meta.description = "Verify commit messages from the default branch to HEAD follow conventional commit format";
             text = ''
-              default_branch=$(git rev-parse --abbrev-ref origin/HEAD | sed 's@origin/@@')
-              current_branch=$(git rev-parse --abbrev-ref HEAD)
+              default_branch=$(git remote show origin | grep 'HEAD branch' | cut -d' ' -f5)
 
-              commit_count=$(git rev-list --count "$default_branch".."$current_branch")
+              commit_count=$(git rev-list --count "$default_branch"..HEAD)
 
               if [ "$commit_count" -eq 0 ]; then
-                  echo "No commits to check between $default_branch and $current_branch."
+                  echo "No commits to check between $default_branch and HEAD."
               else
                   echo "Checking $commit_count commit(s)..."
-                  cz check --rev-range "$default_branch".."$current_branch"
+                  cz check --rev-range "$default_branch"..HEAD
               fi
             '';
           };