Line too long: Attribute chain on left hand side of assignment

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Describe the style change

Sometimes you need to access attributes deep within another object or with extremely long names, and Black helpfully tries to wrap the right hand side of the expression to avoid blowing the length limit, but doesn't touch the right.

Examples in the current Black style

(
    something.something_else.hideously_long_attribute_name.other_property.even_deeper.finally_getting_close.okay
) = 1

Desired style

(
    something
    .something_else
    .hideously_long_attribute_name
    .other_property
    .even_deeper
    .finally_getting_close
    .okay
) = 1

Additional context

My example may evoke appeals to the Law of Demeter, but equally frequent is the issue of very long and descriptive attribute names, not just paths this reductio-ad-absurdum long.