Fix html5lib#67: BufferedStream returns unicode string.

This is a simple case of using a unicode string to join where we
should be using a bytes string.

Author: gsnedders

html5lib/inputstream.py

@@ -114,7 +114,7 @@ def _readFromBuffer(self, bytes):
         if remainingBytes:
             rv.append(self._readStream(remainingBytes))
 
-        return "".join(rv)
+        return b"".join(rv)
 
 
 def HTMLInputStream(source, encoding=None, parseMeta=True, chardet=True):