If a DCP client uses a long (exact length TBD) name when connecting, it can result in
STATS calls (for example performed by ns_server to monitor rebalance) to fail:
Looks like problem is here - we cap the response keyLen to 1 byte for all response types, not just "Response with flex-framing extras" (0x18):
This change was introduced via: http://review.couchbase.org/#/c/86393/
See https://github.com/couchbase/kv_engine/blob/master/docs/BinaryProtocol.md#response-header - it should be permitted to return keys up to 65,535 bytes long for "regular" response packets (0x81).