If push to two feature branches, A and B, which one lands in production? both? if so, how? or the last one you pushed? Or the one that finished its build later?
My specific implementation uses the git commit id. Only the tool for signing cookies actually knows about branches.
So your delivering all commits on all branches to prod? That sounds hairy
How many commits do you do in a day?
The hardest part is figuring out how to do this without a map.
On a big team, potentially 100's. But if your delivering all commits regardless of branches, why even have branches?
Because they're still useful? A branch is a useful tool for the developers who know their development process includes pushing to and pulling from branch "xyz" while they develop whatever feature they're tasked to develop. That they don't solve every problem doesn't bother me.
My live system looks up the branch name in the URL or in a (signed) cookie and checks out the appropriate branch then and there. This is possible because my development system is integrated into my live system.