[utils] Prevent override of custom headers.

The dict of headers of request objects in urllib has its keys always
capitalized.

This causes the lookup to fail and overwrite the header. If for example
a Extractor tries to add a "User-Agent" header the internal
representation in the request object is "User-agent". The header is
therefore clobbered by the "User-Agent" in std_headers, because the
strings are not equal.

diff --git a/youtube_dl/utils.py b/youtube_dl/utils.py
index 98732e8e99036b32eaa7b802a1ed028e85e0f7ae..daf94abd1d541d77e8b74f0f17e6fde780b054e8 100644 (file)
--- a/youtube_dl/utils.py
+++ b/youtube_dl/utils.py
@@ -611,7 +611,9 @@ class YoutubeDLHandler(compat_urllib_request.HTTPHandler):
 
     def http_request(self, req):
         for h, v in std_headers.items():
-            if h not in req.headers:
+            # Capitalize is needed because of Python bug 2275: http://bugs.python.org/issue2275
+            # The dict keys are capitalized because of this bug by urllib
+            if h.capitalize() not in req.headers:
                 req.add_header(h, v)
         if 'Youtubedl-no-compression' in req.headers:
             if 'Accept-encoding' in req.headers: