I'm used to debugging REST-API calls via the browser. Now I'm only getting:

Requested content type is not available. Acceptable types: */*,
application/json 

I'm quite sure this used to work before. The error message itself is
from a commit in May (5744:d4de45cde106) but I'm sure I've debugged REST
in the browser after that date. So a recent change must have affected
that we can no longer view the JSON output from REST-API queries in the
browser.

Any idea?