alias should be derived from cursor's db, not the cursor itself

Author: dcramer

debug_toolbar/utils/tracking/db.py

@@ -57,7 +57,7 @@ def execute(self, sql, params=()):
                 pass
             del cur_frame
 
-            alias = getattr(self, 'alias', 'default')
+            alias = getattr(self.db, 'alias', 'default')
             conn = connections[alias].connection
             # HACK: avoid imports
             if conn: