From eb9ee194221e2fb0c260ead7573280fe06d875e8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sergey=20M=E2=80=A4?= <dstftw@gmail.com>
Date: Mon, 25 Apr 2016 00:03:12 +0600
Subject: [PATCH] [utils] Allow None mimetypes in mimetype2ext

---
 youtube_dl/utils.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/youtube_dl/utils.py b/youtube_dl/utils.py
index f333e47127..7bcc85e2b5 100644
--- a/youtube_dl/utils.py
+++ b/youtube_dl/utils.py
@@ -1935,6 +1935,9 @@ def error_to_compat_str(err):
 
 
 def mimetype2ext(mt):
+    if mt is None:
+        return None
+
     ext = {
         'audio/mp4': 'm4a',
     }.get(mt)