no opinion on tuple assignment parentheses?

This might be intentional but it feels like an omission, so I'm reporting it.

Does Black not have an opinion on parentheses around tuples, when assigning or returning? The following file remains untouched:

(a, b, c) = 1, 2, 3
a, b, c = (1, 2, 3)
return (d, e, f)
return 1, 2, 3

I would expect the optional parentheses would be removed in all above cases, per this: "In those cases, parentheses are removed when the entire statement fits in one line, or if the inner expression doesn't have any delimiters to further split on."

Operating system: Linux Mint
Python version: 3.6
Black version: 18.6b4
Does also happen on master: yes

The issue names no files or tests. Reproduce the four Python examples with Black 18.6b4 or current master, compare the output with the quoted parenthesis rule, and trace the formatter behavior for tuple assignment and return statements. Done means the chosen behavior is covered by regression tests and is consistent with Black's documented formatting rules.