This must answer the question, where did you see the content identified by a given hash (hash being sha1, sha1_git, sha256.
The expected answer is of the form: "content <foo> appeared in revision <bar> which we have seen in visit <X> of origin <quux> with path <xxuq>"

This replaces the old route /api/1/browse/algo_hash:content_hash.
(deactivated in c2a466e61e6408addb135b922246fb87fcfbff30).