Appengine数据存储已损坏，如何重置

I am using Go + Google AppEngine, and it seems like I have caused my datastore to become corrupted. I ran a query with Filter("ContentId !=", val), and apparently that is not a supported operation. Moreover, it corrupted my database! When I go to localhost:8000/datastore, I get a long stack trace that ends with:

  File "/Users/me/go_appengine/google/appengine/api/yaml_listener.py", line 177, in _HandleEvents
raise yaml_errors.EventError(e, event_object)
EventError: could not determine a constructor for the tag '!ContentId'
  in "<string>", line 15, column 11:
      - name: !ContentId
              ^
  in "<string>", line 15, column 11:
      - name: !ContentId

It looks like it made a tag labeled !ContentId.

My question is, how do I reset the datastore to remove this corrupted dev_appserver.py --clear_datastore=yes myapp, but that does not fix it.

To remove the tag edit your index.yaml file in your project root and deploy it again.
!= is not in the list of supported property filters for golang.

If you'd provide your full query and some context we may come up with a good workaround.