Right-clicking on a brewing stand's input does not split the stack

Right-clicking on a stack of items generally splits it in half; but on the input slot of a Brewing Stand, it picks up the entire stack.

Also, if I have some of an item in the stand and some in my inventory, shift-clicking the stack in my inventory does not add it to the stack in the stand, which seems like it could be related (and is unlike the behavior in e.g. a furnace's fuel slot).