Fix multiprocessing regression in update_index

4e1e2e1 introduced a bug because it
used a property name which exists on haystack.ConnectionHandler but not
the Django ConnectionHandler class it's modeled on. Long-term, we should
rename the Haystack class to something like `SearchConnectionHandler`
to avoid future confusion.

Closes django-haystack#1449

Author: acdha

haystack/management/commands/update_index.py

@@ -42,10 +42,10 @@ def update_worker(args):
         if 'sqlite3' not in info['ENGINE']:
             try:
                 close_old_connections()
-                if isinstance(connections.thread_local.connections, dict):
-                    del connections.thread_local.connections[alias]
+                if isinstance(connections._connections, dict):
+                    del connections._connections[alias]
                 else:
-                    delattr(connections.thread_local.connections, alias)
+                    delattr(connections._connections, alias)
             except KeyError:
                 pass