Change registry code to disconnect from the DB before long I/O operations

endpoints/verbs.py

@@ -101,6 +101,9 @@ def get_squashed_tag(namespace, repository, tag):
         logger.debug('Redirecting to download URL for derived image %s', derived.uuid)
         return redirect(download_url)
 
+      # Close the database handle here for this process before we send the long download.
+      database.close_db_filter(None)
+
       logger.debug('Sending cached derived image %s', derived.uuid)
       return send_file(store.stream_read_file(derived.locations, derived_layer_path))