2 simultanous merges will break one of the release builds

[mockitoguy]

Problem

When 2 PRs are merged in a short time, there is a chance the Travis CI release builds will overlap. This will cause both builds to fail. Consider the sequence:

1. merge PR 'A', build 'A' starts
2. merge PR 'B' (clean merge, no conflicts), build 'B' starts even though 'A' hasn't finished
3. 'A' build fails on 'git push' because remote branch has new commit (merge commit from PR 'B', the previous step)
4. 'B' build should succeed in theory and release a new version. The new version will contain both PRs / both changes.

Considerations

• I might be wrong with above sequence, I have written it based on my memory of how Shipkit works. We need to try it out.
• It is not ideal that we ship a single version that contains multiple changes (it's end of the world, either)

Suggested solution

TBD. Any ideas? How important is fixing this issue?

[mockitoguy]

Oups, it's a duplicate :) I just saw the ticket from @epeee #395