Multiple assignments result in wrong parameters

[dearblue]

% bin/mruby -e 'def m((x, y, z), &b) { x:, y:, z:, b: } end; p m([1, 2, 3]) {}'
{:x=>1, :y=>2, :z=>3, :b=>[1, 2, 3]}

This happens in the latest master (commit ad3ce7b) and 3.1.0-rc (commit f29924c).
The triggering commit seems to be 9e064f2.
I tried revert and got the expected result.

% bin/mruby -e 'def m((x, y, z), &b) { x:, y:, z:, b: } end; p m([1, 2, 3]) {}'
{:x=>1, :y=>2, :z=>3, :b=>#<Proc:0x800e300f0@-e:1>}