The added test only exercised a 403 with a single range, leaving three
paths that were equally broken untested: a suffix range, whose first_pos
is still -1 when the bounds asserts are compiled out under NDEBUG; two
ranges, where apply_ranges() makes no boundary for a non-206 response and
the multipart branch wrote an empty one; and a 2xx that is not a 206,
which was validated but still announced the full content length.
Fold the copied route back into /streamed-with-range with a status query
parameter, following the ?error idiom already used there.
5539a66c63
