[generic] simply use urljoin

youtube_dl/extractor/generic.py

@@ -7,8 +7,8 @@ from .common import InfoExtractor
 from ..utils import (
     compat_urllib_error,
     compat_urllib_parse,
-    compat_urllib_parse_urlparse,
     compat_urllib_request,
+    compat_urlparse,
 
     ExtractorError,
 )
@@ -163,15 +163,7 @@ class GenericIE(InfoExtractor):
             raise ExtractorError(u'Invalid URL: %s' % url)
 
         video_url = compat_urllib_parse.unquote(mobj.group(1))
-        if video_url.startswith('//'):
+        video_url = compat_urlparse.urljoin(url, video_url)
-            video_url = compat_urllib_parse_urlparse(url).scheme + ':' + video_url
-        if '://' not in video_url:
-            up = compat_urllib_parse_urlparse(url)
-            if video_url.startswith('/'):
-                video_url = up.scheme + '://' + up.netloc + video_url
-            else:  # relative path
-                video_url = (up.scheme + '://' + up.netloc +
-                             up.path.rpartition('/')[0] + '/' + video_url)
         video_id = os.path.basename(video_url)
 
         # here's a fun little line of code for you: