Experimental notification hits channel for build cancellation

Steps to reproduce:

  1. Wait on CircleCI index page for my project
  2. Push a new branch
  3. As soon as the branch appears on index page, cancel it
    Current: Error “Canceled: <repo/branch info>” is sent to Slack
    Expected: since we are using the experimental notifications feature, we shouldn’t be notified to slack for this non-master branch.

From circle.yml:

experimental:
  notify:
    branches:
      only:
        - deployed
        - master

I expect this is just a race condition since the project hasn’t finished cloning yet, but perhaps a fallback to current circle.yml off of last master branch build would be a good alternative?

Also seeing this, is there a plan to resolve?