`Base.merge` gives incorrect results for `Base.Pairs` + `NameTuple`

[topolarity]

julia> merge((; a = 1), Base.Pairs((; b = 2, c = 3), (:b,)))
(a = 1, b = 2, c = 3)

julia> merge((; a = 1), collect(Base.Pairs((; b = 2, c = 3), (:b,))))
(a = 1, b = 2)

Noticed in #59269 (comment)

[adienes]

I think this is a bug in values(::Pair), not merge, right?
nvm, I see they both access .data causing the same issue

due to this method with an apt TODO

values(v::Pairs) = getfield(v, :data) # TODO: this should be a view of data subset by itr

the docstring promises

keys(a), values(a) and pairs(a) all iterate a and return the elements in the same order.

but that is not the case for Pairs

[JeffBezanson]

I don't think Pairs is currently intended to support subsets of keys, it was maybe a planned future feature. The only reason for the itr field AFAICT is to support alternate key sets, specifically linear or cartesian indices for arrays.