Added stream rewind in JsonResponse constructor

src/Response/JsonResponse.php

@@ -61,6 +61,7 @@ public function __construct(
     ) {
         $body = new Stream('php://temp', 'wb+');
         $body->write($this->jsonEncode($data, $encodingOptions));
+        $body->rewind();
 
         $headers = $this->injectContentType('application/json', $headers);
 

test/Response/JsonResponseTest.php

@@ -126,4 +126,13 @@ public function testUsesSaneDefaultJsonEncodingFlags($value, $key)
             sprintf('Did not encode %s properly; expected (%s), received (%s)', $key, $expected, $contents)
         );
     }
+
+    public function testConstructorRewindsBodyStream()
+    {
+        $json = ['test' => 'data'];
+        $response = new JsonResponse($json);
+
+        $actual = json_decode($response->getBody()->getContents(), true);
+        $this->assertEquals($json, $actual);
+    }
 }