Keep committed release note reads offline

internal/git/source.go

@@ -116,11 +116,11 @@ func ReadCommitFile(ctx context.Context, repositoryDir, commit, name string) ([]
 	if !validObjectID(commit) || name == "" || path.IsAbs(name) || path.Clean(name) != name || strings.HasPrefix(name, "../") || name == ".." || strings.Contains(name, "\\") {
 		return nil, fmt.Errorf("invalid committed file identity %q at %q", name, commit)
 	}
-	content, err := run(ctx, repositoryDir, nil, "show", commit+":"+name)
+	content, err := readLocalObjects(ctx, repositoryDir, nil, "show", commit+":"+name)
 	if err != nil {
 		return nil, fmt.Errorf("read committed file %q: %w", name, err)
 	}
-	return []byte(content), nil
+	return content, nil
 }
 
 // CommittedPaths resolves individual paths from captured objects. It requests

internal/git/source_test.go

@@ -88,6 +88,11 @@ func TestCandidateObjectReadsStayLocalInPartialClones(t *testing.T) {
 			if _, err := ReadTree(t.Context(), repository, fixture.commit); err == nil {
 				t.Fatal("tree inspection succeeded with unavailable objects")
 			}
+			_, fileErr := ReadCommitFile(t.Context(), repository, fixture.commit, "source.txt")
+			var fileExitError *exec.ExitError
+			if !errors.As(fileErr, &fileExitError) {
+				t.Fatalf("committed file error %v lost its Git process cause", fileErr)
+			}
 			_, err := ReadBlob(t.Context(), repository, blob)
 			var exitError *exec.ExitError
 			if !errors.As(err, &exitError) {