Merge pull request #470 from takeflight/feature/admin-hook-decorator

Return the function again from the hook decorator

wagtail/wagtailcore/hooks.py

@@ -25,7 +25,10 @@ def register(hook_name, fn=None):
 
     # Pretend to be a decorator if fn is not supplied
     if fn is None:
-        return lambda fn: register(hook_name, fn)
+        def decorator(fn):
+            register(hook_name, fn)
+            return fn
+        return decorator
 
     if hook_name not in _hooks:
         _hooks[hook_name] = []