Merge branch '4.3' into 4.4

* 4.3:
  [HttpKernel] fix merge
  fix tests
  [HttpClient] fix throwing HTTP exceptions when the 1st chunk is emitted

Author: nicolas-grekas

Response/ResponseTrait.php

@@ -339,20 +339,28 @@ public static function stream(iterable $responses, float $timeout = null): \Gene
                         } elseif ($chunk instanceof ErrorChunk) {
                             unset($responses[$j]);
                             $isTimeout = true;
-                        } elseif ($chunk instanceof FirstChunk && $response->logger) {
-                            $info = $response->getInfo();
-                            $response->logger->info(sprintf('Response: "%s %s"', $info['http_code'], $info['url']));
+                        } elseif ($chunk instanceof FirstChunk) {
+                            if ($response->logger) {
+                                $info = $response->getInfo();
+                                $response->logger->info(sprintf('Response: "%s %s"', $info['http_code'], $info['url']));
+                            }
+
+                            yield $response => $chunk;
+
+                            if ($response->initializer && null === $response->info['error']) {
+                                // Ensure the HTTP status code is always checked
+                                $response->getHeaders(true);
+                            }
+
+                            continue;
                         }
 
                         yield $response => $chunk;
                     }
 
                     unset($multi->handlesActivity[$j]);
 
-                    if ($chunk instanceof FirstChunk && null === $response->initializer && null === $response->info['error']) {
-                        // Ensure the HTTP status code is always checked
-                        $response->getHeaders(true);
-                    } elseif ($chunk instanceof ErrorChunk && !$chunk->didThrow()) {
+                    if ($chunk instanceof ErrorChunk && !$chunk->didThrow()) {
                         // Ensure transport exceptions are always thrown
                         $chunk->getContent();
                     }