x/net/http2: h2spec violation 6.10.1

[fraenkel]

$ ./h2spec -S -k -t -h 127.0.0.1 -p 8080 http2/6.10/1
Hypertext Transfer Protocol Version 2 (HTTP/2)
  6. Frame Definitions
    6.10. CONTINUATION
      × 1: Sends multiple CONTINUATION frames preceded by a HEADERS frame
        -> The endpoint must accept the frame.
           Expected: HEADERS Frame (stream_id:1)
             Actual: Connection closed

[fraenkel]

This one is valid.
There is no handling of a HEADER (END_HEADERS=false) + CONTINUATION.

[fraenkel]

My server had a MaxHeaderBytes set too low for this test. Once I increased it above the limit needed, the test passes.