Let youtube IE handle IDs starting with PL (Closes #572)

test/test_youtube_playlist_ids.py

@@ -0,0 +1,22 @@
+#!/usr/bin/env python
+
+import sys
+import unittest
+
+# Allow direct execution
+import os
+sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+from youtube_dl.InfoExtractors import YoutubeIE, YoutubePlaylistIE
+
+class TestYoutubePlaylistMatching(unittest.TestCase):
+    def test_playlist_matching(self):
+        assert YoutubePlaylistIE().suitable(u'ECUl4u3cNGP61MdtwGTqZA0MreSaDybji8')
+        assert YoutubePlaylistIE().suitable(u'PL63F0C78739B09958')
+        assert not YoutubePlaylistIE().suitable(u'PLtS2H6bU1M')
+
+    def test_youtube_matching(self):
+        assert YoutubeIE().suitable(u'PLtS2H6bU1M')
+
+if __name__ == '__main__':
+    unittest.main()