Fixed a bug

The data dictionary was getting overwritten by the session_hash rather
than just being added to the rest of the data dictionary.

Author: zardaloop

openml/apiconnector.py

@@ -891,7 +891,7 @@ def _read_url(self, url, add_authentication=False, data=None):
         if data is None:
             data = {}
         if add_authentication:
-            data = {'session_hash': self._session_hash}
+            data['session_hash'] = self._session_hash
         data = urlencode(data)
         data = data.encode('utf-8')