[utils] YoutubeDLHandler: don't use 'Youtubedl-user-agent' for overriding the default user agent

Setting the 'User-Agent' header is enough

youtube_dl/downloader/http.py

@@ -25,7 +25,7 @@ class HttpFD(FileDownloader):
         # Do not include the Accept-Encoding header
         headers = {'Youtubedl-no-compression': 'True'}
         if 'user_agent' in info_dict:
-            headers['Youtubedl-user-agent'] = info_dict['user_agent']
+            headers['User-agent'] = info_dict['user_agent']
         if 'http_referer' in info_dict:
             headers['Referer'] = info_dict['http_referer']
         add_headers = info_dict.get('http_headers')

youtube_dl/extractor/atresplayer.py

@@ -95,7 +95,7 @@ class AtresPlayerIE(SubtitlesInfoExtractor):
         for fmt in ['windows', 'android_tablet']:
             request = compat_urllib_request.Request(
                 self._URL_VIDEO_TEMPLATE.format(fmt, episode_id, timestamp_shifted, token))
-            request.add_header('Youtubedl-user-agent', self._USER_AGENT)
+            request.add_header('User-Agent', self._USER_AGENT)
 
             fmt_json = self._download_json(
                 request, video_id, 'Downloading %s video JSON' % fmt)

youtube_dl/extractor/bliptv.py

@@ -199,7 +199,7 @@ class BlipTVIE(SubtitlesInfoExtractor):
         # For some weird reason, blip.tv serves a video instead of subtitles
         # when we request with a common UA
         req = compat_urllib_request.Request(url)
-        req.add_header('Youtubedl-user-agent', 'youtube-dl')
+        req.add_header('User-Agent', 'youtube-dl')
         return self._download_webpage(req, None, note=False)
 
 

youtube_dl/extractor/mtv.py

@@ -53,7 +53,7 @@ class MTVServicesInfoExtractor(InfoExtractor):
         webpage_url = self._MOBILE_TEMPLATE % mtvn_id
         req = compat_urllib_request.Request(webpage_url)
         # Otherwise we get a webpage that would execute some javascript
-        req.add_header('Youtubedl-user-agent', 'curl/7')
+        req.add_header('User-Agent', 'curl/7')
         webpage = self._download_webpage(req, mtvn_id,
                                          'Downloading mobile page')
         metrics_url = unescapeHTML(self._search_regex(r'<a href="(http://metrics.+?)"', webpage, 'url'))

youtube_dl/utils.py

@@ -606,11 +606,6 @@ class YoutubeDLHandler(compat_urllib_request.HTTPHandler):
             if 'Accept-encoding' in req.headers:
                 del req.headers['Accept-encoding']
             del req.headers['Youtubedl-no-compression']
-        if 'Youtubedl-user-agent' in req.headers:
-            if 'User-agent' in req.headers:
-                del req.headers['User-agent']
-            req.headers['User-agent'] = req.headers['Youtubedl-user-agent']
-            del req.headers['Youtubedl-user-agent']
 
         if sys.version_info < (2, 7) and '#' in req.get_full_url():
             # Python 2.6 is brain-dead when it comes to fragments