If I tell the autobuilder to build master, I'm expecting it to resolve HEAD at the time I push the button. If I then push more changes to a branch whilst its building, the revision the autobuilder builds currently changes depending on when the checkout happens. This is not desirable and leads to confusing builds results.
The issue here is that we're setting the commit to check out to be HEAD. As we don't want nightly to checkout every repo utilized in what it triggers, so we never resolve it in the triggered build. We just pass the commit id as HEAD which leads to this issue. This is actually the expected behavior although I will agree that it's not the desired behavior.
Currently testing. This has quite a number of corner cases due to our ability to mix and match repo/branch/tag. Final move to production pending testing.
Fixed as of: http://git.yoctoproject.org/cgit/cgit.cgi/yocto-autobuilder/commit/?id=1f4b9b6575b1ba01bc82a39b9c63d7474a295163