The branches that are being merged are tested, also in the first version. However, different branches can conflict with each other, and break the master builds. This was happening often enough for us to want to prevent this.
The simple way would be to rebase your branch (or merge in master). However, with the amount of changes that are being merged, by the time the CI result comes in for your rebased branch, the tip of master is already changed making the CI result obsolete. So we went for the queue approach instead.
The simple way would be to rebase your branch (or merge in master). However, with the amount of changes that are being merged, by the time the CI result comes in for your rebased branch, the tip of master is already changed making the CI result obsolete. So we went for the queue approach instead.