[extractor/common] fix _get_cookies method for python 2(#20673, #23256, #20326, closes #28640)

youtube_dl/extractor/common.py

@@ -2899,7 +2899,10 @@ class InfoExtractor(object):
         """ Return a compat_cookies.SimpleCookie with the cookies for the url """
         req = sanitized_Request(url)
         self._downloader.cookiejar.add_cookie_header(req)
-        return compat_cookies.SimpleCookie(req.get_header('Cookie'))
+        cookie = req.get_header('Cookie')
+        if cookie and sys.version_info[0] == 2:
+            cookie = str(cookie)
+        return compat_cookies.SimpleCookie(cookie)
 
     def _apply_first_set_cookie_header(self, url_handle, cookie):
         """