Travis CI doesn’t seem to build new Draft PRs.
So far I opened three PRs in Draft state in two different repositories, neither triggered a build nor received any status from Travis CI.
Closing and reopening doesn’t help either (as this used to fix similar issues earlier).
Verified that GitHub send a webhook event about the new PRs, all were acknowledged by Travis CI API with HTTP 204.
Reference request IDs:
Environment: Open-source repository on travis-ci.org, not using Checks API.
Draft PRs is a new feature added on 14/2/2019, see https://twitter.com/github/status/1096093162345508864.