c-hyper: fix multi-request mechanism

It makes test 565 run fine.

Fixes #8896
Closes #10080
Assisted-by: Daniel Stenberg

lib/c-hyper.c

@@ -699,6 +699,7 @@ static int uploadstreamed(void *userdata, hyper_context *ctx,
 {
   size_t fillcount;
   struct Curl_easy *data = (struct Curl_easy *)userdata;
+  struct connectdata *conn = (struct connectdata *)data->conn;
   CURLcode result;
   (void)ctx;
 
@@ -713,7 +714,15 @@ static int uploadstreamed(void *userdata, hyper_context *ctx,
     return HYPER_POLL_PENDING;
   }
 
-  result = Curl_fillreadbuffer(data, data->set.upload_buffer_size, &fillcount);
+  if(data->req.upload_chunky && conn->bits.authneg) {
+    fillcount = 0;
+    data->req.upload_chunky = FALSE;
+    result = CURLE_OK;
+  }
+  else {
+    result = Curl_fillreadbuffer(data, data->set.upload_buffer_size,
+                                 &fillcount);
+  }
   if(result) {
     data->state.hresult = result;
     return HYPER_POLL_ERROR;
@@ -1166,7 +1175,12 @@ CURLcode Curl_http(struct Curl_easy *data, bool *done)
 
   Curl_debug(data, CURLINFO_HEADER_OUT, (char *)"\r\n", 2);
 
-  data->req.upload_chunky = FALSE;
+  if(data->req.upload_chunky && conn->bits.authneg) {
+    data->req.upload_chunky = TRUE;
+  }
+  else {
+    data->req.upload_chunky = FALSE;
+  }
   sendtask = hyper_clientconn_send(client, req);
   if(!sendtask) {
     failf(data, "hyper_clientconn_send");

tests/data/DISABLED

@@ -65,7 +65,6 @@
 # listed below
 %if hyper
 266
-565
 579
 587
 # 1021 re-added here due to flakiness