Actually, it has msnbot listed, and according to this http://www.bing.com/community/site_blogs/b/webmaster/archive/2010/06/28/bing-crawler-bingbot-on-the-horizo

Actually, it has msnbot listed, and according to this http://www.bing.com/community/site_blogs/b/webmaster/archive/2010/06/28/bing-crawler-bingbot-on-the-horizon.aspx http://www.bing.com/community/site_blogs/b/webmaster/archive... The bingbot will respect msnbot permissions when it doesn't see bingbot, unless of course github has explicitly blocked unrecognized user agents too.