It's been hard to debug travis failures for a long time, and since the recent credentials-issue[1] being handled poorly, I think we can close this chapter.
> After 3 days of pressure from multiple projects, [Travis CI] silently patched the issue on the 10th. No analysis, no security report, no post mortem, not warning any of their users that their secrets might have been stolen
[1] https://arstechnica.com/information-technology/2021/09/travis-ci-flaw-exposed-secrets-for-thousands-of-open-source-projects/