[internal-branch.go1.16-vendor] http2: remove check for read-after-close of request bodies

Aborting a request currently races with writes of the request
body, so abortRequestBodyWrite can close the body before writeRequestBody
reads from it.

Updates golang/go#49076

Change-Id: I5362283f4066611aeecbc48b400d79cfa0b4b284
Reviewed-on: https://go-review.googlesource.com/c/net/+/351972
Trust: Damien Neil <[email protected]>
Run-TryBot: Damien Neil <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Brad Fitzpatrick <[email protected]>
Reviewed-on: https://go-review.googlesource.com/c/net/+/356984
Reviewed-by: Dmitri Shuralyov <[email protected]>

Author: neild

http2/transport_test.go

@@ -4969,7 +4969,10 @@ func (rc *closeChecker) Read(b []byte) (n int, err error) {
 	select {
 	default:
 	case <-rc.closed:
-		panic("read from closed body")
+		// TODO(dneil): Consider restructuring the request write to avoid reading
+		// from the request body after closing it, and check for read-after-close here.
+		// Currently, abortRequestBodyWrite races with writeRequestBody.
+		return 0, errors.New("read after Body.Close")
 	}
 	return rc.ReadCloser.Read(b)
 }