Both get updates. Someone will do a rebase of B to the most-recent A and push that. (In my previous workplaces they would have just pulled the most recent A)
Here's where the confusion comes in: If I get the updated B but A has updated again, I cannot pull A nor rebase to A and successfully push the result without forcing. IIRC, on push it complains that my local branch is not up to date, but if I pull it will tell me I am up to date.
At least, that's what I think is the timing - since this involves multiple people I'm uncertain of what exactly occurs and the order, nor why problems are inconsistent. We don't have that many feature branches that have multiple people contributing AND requiring updates from the master branch, but it happens often enough.
