You can access the plugins trac revision log rss feed by using the format:
plugins.trac.wordpress/log/plugin_name?format=rss&limit=100&mode=stop_on_copy
Example: feed link for the jetpack plugin revision log.
The revision log rss feed will only contain direct links to changeset diffs for any file committed with changes.
Example changeset link.
You can also access the feed link directly from the plugin page on WordPres.org:
