From e2f61598be49b75f16b501f7a4d24f4c8c230c49 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sergey=20M=E2=80=A4?= <dstftw@gmail.com>
Date: Mon, 17 Sep 2018 22:14:28 +0700
Subject: [PATCH] [twitch] Don't pollute default headers dict

---
 youtube_dl/extractor/twitch.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/youtube_dl/extractor/twitch.py b/youtube_dl/extractor/twitch.py
index 26661fdf6..401615683 100644
--- a/youtube_dl/extractor/twitch.py
+++ b/youtube_dl/extractor/twitch.py
@@ -51,7 +51,9 @@ def _handle_error(self, response):
                 expected=True)
 
     def _call_api(self, path, item_id, *args, **kwargs):
-        kwargs.setdefault('headers', {})['Client-ID'] = self._CLIENT_ID
+        headers = kwargs.get('headers', {}).copy()
+        headers['Client-ID'] = self._CLIENT_ID
+        kwargs['headers'] = headers
         response = self._download_json(
             '%s/%s' % (self._API_BASE, path), item_id,
             *args, **compat_kwargs(kwargs))