Black 19.10b0 breaks subscript with 1D tuple

Black v19.10b0

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This should be left alone:

a = a[:2,]

But it becomes:

a = a[
    :2,
]

[Rysias]

I seem to still have this issue with version 21.9b0

[jorisvandenbossche]

Note that several explanations in the black docs / README are also no longer correct (if it is the intention to keep this specific change).

Eg in the section on “Trailing commas”:

One exception to removing trailing commas is tuple expressions with just one element. In this case Black won’t touch the single trailing comma as this would unexpectedly change the underlying data type. Note that this is also the case when commas are used while indexing. This is a tuple in disguise: numpy_array[3, ].

or in “How Black wraps lines”:

As for vertical whitespace, Black tries to render one full expression or simple statement per line. If this fits the allotted line length, great.

# in:

j = [1,
    2,
    3,
]

# out:

j = [1, 2, 3]