Multiple assignment evaluation order has been made consistent with
single assignment evaluation order. With single assignment, Ruby
uses a left-to-right evaluation order. With this code:

foo[0] = bar

The following evaluation order is used:

1. foo
2. bar
3. []= called on the result of foo

In Ruby before 3.1.0, multiple assignment did not follow this
evaluation order. With this code:

foo[0], bar.baz = a, b

Versions of Ruby before 3.1.0 would evaluate in the following
order

1. a
2. b
3. foo
4. []= called on the result of foo
5. bar
6. baz= called on the result of bar

Starting in Ruby 3.1.0, the evaluation order is now consistent with
single assignment, with the left-hand side being evaluated before
the right-hand side:

1. foo
2. bar
3. a
4. b
5. []= called on the result of foo
6. baz= called on the result of bar

[[Bug #4443]]