TRAVIS_COMMIT is not the commit initially checked out

[native-api]

I think I know what’s happening. For a PR build, Travis actually retrieves origin/refs/pull/<PR#>/merge – a “merge preview” commit generated by Github.

Looks like it’s generated anew each time the PR branch or the base branch changes:

Build stages get different codebases if the PR branch or the base branch changes in the meantime

AFAICS, the problem is that Travis fetches a “merge preview” commit autogenerated by Github, +refs/pull/<PR#>/merge. Which is regenerated by Github whenever the PR branch or the base branch changes. This is a legitimate bug – but I don’t know whether it’s possible to get this commit any other way that would be protected from this effect. Since you are an enterprise customer, you can report this bug directly to Enterprise support at enterprise@travis-ci.com and refer to this topic.

I don’t know if there’s some other way to retrieve that merge preview commit that would allow one to retrieve an earlier version of it that would correspond to the time the specific PR commit was pushed.