For massigns, we have special handling for the case where the massign is only one item, e.g. foo, = [1, 2], since that comma produces different behavior at runtime. However, Ruby also considers *foo = [1, 2] an massign, even though there's only one item and no comma. Ruby also doesn't consider *foo, = [1, 2] valid syntax, so we shouldn't render that final comma when the only item in an massign is a rest param.
Resolves #392
For massigns, we have special handling for the case where the massign is only one item, e.g.
foo, = [1, 2], since that comma produces different behavior at runtime. However, Ruby also considers*foo = [1, 2]an massign, even though there's only one item and no comma. Ruby also doesn't consider*foo, = [1, 2]valid syntax, so we shouldn't render that final comma when the only item in an massign is a rest param.