404. That’s an error.

The requested URL /custom?q=%22regular+expression%22&client=google-coop-np&cof=FORID:13%3BAH:left%3BS:http://www.emacswiki.org/%3BCX:Emacs%2520Wiki%2520Search%3BL:http://www.emacswiki.org/emacs_rss.png%3BLH:43%3BLP:1%3BVLC:%23551a8b%3BDIV:%23cccccc%3B&cx=004774160799092323420:6-ff2s0o6yi&adkw=AELymgUpjZz99vqYZ1EA32rQJcDcC6kFXiJf4PoFQi9_CxUvDxTJx2t0ZtQST4bQdz3nUm8w-c9vhaeDqMOGx4-PMWvxdk08mUlYhVzXb4ffKFRQpDc7WPs&hl=en&boostcse=0&ie=UTF-8&oe=UTF-8&prmd=ivns&ei=Tn9GV-O6OYzBmwHoy56ADA&start=20&sa=N was not found on this server. That’s all we know.