Unnecessary parentheses added to expression in indexed assignment

[Pabloo22]

Describe the bug

Black unnecessarily adds parentheses around the right-hand side expression in indexed assignments when breaking lines for long index names. This results in added visual clutter and does not conform to typical Python formatting standards where no additional parentheses would be expected. In particular, PyLint raises the superfluous-parens warning.

To Reproduce

Given the following Python script:

import numpy as np

def main():
    dictionary_of_arrays = {
        "long_key_name_for_the_example": np.zeros((3, 1)),
        "short": np.zeros((3, 1)),
    }
    index_zero = 0
    very_long_index_name = 1
    dictionary_of_arrays["long_key_name_for_the_example"][very_long_index_name, index_zero] = 10 - 5

When formatted using the online Black formatter at https://black.vercel.app/?version=main, the assignment line is formatted as follows:

dictionary_of_arrays["long_key_name_for_the_example"][
    very_long_index_name, index_zero
] = (10 - 5)

Expected behavior

The expected code should look like this:

dictionary_of_arrays["long_key_name_for_the_example"][
    very_long_index_name, index_zero
] = 10 - 5

Environment

• Black's version: main (online formatter)
• OS and Python version: N/A (used the online formatter)

Additional context

None.