GitHub Release event is not executed by Starlark

Drone Support
1

I am using drone with Starlark.
If I do release in GitHub(by browser), below code is executed name of “etc”.
but I want to execute name of ‘tag’.

def main(ctx):
  if ctx.build.event == "tag":
    return test("tag")
  else:
    return test("etc")
    
def test(tag):
  return {
    'kind': 'pipeline',
    'name': 'test',
    'steps': [
      {
        'name': tag,
        'image': 'node:10.16.0-alpine',
        'commands': [
          'npm -v',
        ],
      },
    ],
  }

Note that, If I use below .drone.yml, It is executed name of “tag”.

kind: pipeline
name: etc

steps:
- name: etc
  image: node:10.16.0-alpine
  commands:
    - npm -v

trigger:
  event:
    exclude:
      - tag

---

kind: pipeline
name: tag

steps:
- name: tag
  image: node:10.16.0-alpine
  commands:
    - npm -v

trigger:
  event:
    - tag

Is this a specification?