I would expect this to be left alone by the magic trailing comma rule:

zero(
    one,
).two(
    three,
).four(
    five,
)

But Black implodes it to

zero(one,).two(three,).four(
    five,
)

Environment (please complete the following information):

• Version: 20.8b1
• OS and Python version: Linux/Python 3.8.5

Does this bug also happen on master? Yes (playground)