Why has codecov commented on this pull when I didn't run it?

Codecov recently commented on one of our pull requests: https://github.com/dials/dials/pull/824#issuecomment-503999901

The confusing thing is, we don’t currently generate or upload coverage reports for pull requests, and the CI jobs that deal with coverage definitely didn’t run. I thought perhaps codecov was cleverly recognising that the pull request was only removing files, but the coverage hasn’t changed at all, and the pull page at https://codecov.io/gh/dials/dials/pull/824 has every folder as “new” and no commits listed.

Is this a bug or some niche feature that I’m not understanding?