Destructuring syntax does not respect const annotation

[zengmao]

The const keyword seems to have no effect when used with the destructuring syntax in Julia 1.7+.

julia> t = (;a = 1, b = 2);

julia> const (;a, b) = t
(a = 1, b = 2)

julia> a = 3 # re-definition produces no error or warning, so a is not const
3

My Julia version is 1.8.2, 64-bit Linux (glibc), installed from the binary tarball.
(First posted on Discourse: https://discourse.julialang.org/t/destructuring-syntax-does-not-respect-const-annotation/88751)