Make r2c export helper exit cleanly after streaming

scripts/export_r2c_layout.py

@@ -5,6 +5,7 @@ from __future__ import annotations
 
 import argparse
 import json
+import os
 import shutil
 from itertools import islice
 from pathlib import Path
@@ -98,7 +99,8 @@ def main() -> None:
                     json.dump(metadata, f, separators=(",", ":"))
                 seen.add(metadata_fn)
 
-    print(f"Wrote r2c-compatible VCR layout to {args.output_dir}")
+    print(f"Wrote r2c-compatible VCR layout to {args.output_dir}", flush=True)
+    os._exit(0)
 
 
 if __name__ == "__main__":