citricsquid/httpstatus.es — pull request #10 by dogweather (2014-03-07 07:09:13+00:00)
Title: 308 seems to be an official IETF experimental code

It looks like there were two proposed uses of 308, and this one won. See:

http://en.wikipedia.org/wiki/List_of_HTTP_status_codes#3xx_Redirection
https://datatracker.ietf.org/doc/draft-reschke-http-status-308/