From 4ffdb3a35c1eb5bf1f3501a3a24b12f0e232fe29 Mon Sep 17 00:00:00 2001
From: Andrew Svetlov <andrew.svetlov@gmail.com>
Date: Fri, 13 Oct 2017 12:11:02 +0300
Subject: [PATCH] Postfix #2319: Don't set content type twice

---
 aiohttp/web_fileresponse.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/aiohttp/web_fileresponse.py b/aiohttp/web_fileresponse.py
index 04e4256ff77..9c589ddb3c7 100644
--- a/aiohttp/web_fileresponse.py
+++ b/aiohttp/web_fileresponse.py
@@ -186,9 +186,10 @@ def prepare(self, request):
             ct, encoding = mimetypes.guess_type(str(filepath))
             if not ct:
                 ct = 'application/octet-stream'
+            should_set_ct = True
         else:
-            ct = self.headers[hdrs.CONTENT_TYPE]
             encoding = 'gzip' if gzip else None
+            should_set_ct = False
 
         status = HTTPOk.status_code
         file_size = st.st_size
@@ -228,7 +229,8 @@ def prepare(self, request):
             status = HTTPPartialContent.status_code
 
         self.set_status(status)
-        self.content_type = ct
+        if should_set_ct:
+            self.content_type = ct
         if encoding:
             self.headers[hdrs.CONTENT_ENCODING] = encoding
         if gzip: