Priority of breaking subscripts vs breaking previous elements

[dhalbert]

Describe the style change A subscript at the end of a long line of parenthesized elements gets broken in an odd way. The length must be just slightly over the line length.

Examples in the current Black style

The length is crucial. The last element must be, e.g., 12345 or 123456 to make this happen

a = (123, 123, 123, 123, 123, 123, 123, 123, 123, 123, 123, 123, 123, 123, 123, 12345)[
    0
]

Desired style
(A last element of 1234567 would generate something like this, so it's an edge case.)

a = (
    123,
    123,
    123,
    123,
    123,
    123,
    123,
    123,
    123,
    123,
    123,
    123,
    123,
    123,
    123,
    12345,
)[0]

This is not terrible, but I was just startled by it when I saw it.

[graingert]

there seems to be a few duplicates of this:

#814
#1101
#1406

[ichard26]

Indeed this is a duplicate of #814. Thanks for the formatting suggestion!