N5008 [vector.bool.pspc]/2 says:

Unless described below, all operations have the same requirements and semantics as the primary `vector` template, except that operations dealing with the `bool` value type map to bit values in the container storage and `allocator_traits::construct` ([allocator.traits.members]) is not used to construct these values.

[container.alloc.reqmts]/5 says:

Mandates: `allocator_type::value_type` is the same as `X::value_type`.

Is vector<bool, allocator<int>> forbidden? There's implementation divergence: MSVC's STL enforces the mandate, while libc++ and libstdc++ accept this code, discovered while running libc++'s tests with MSVC's STL.

Preferred resolution: I would be satisfied with resolving this as NAD, with a record that LWG believes that "all operations have the same requirements" means that the Mandate applies. I suppose that an editorial note could also be added to this effect, although I don't believe it's necessary.

Alternate resolution: If LWG believes that the Mandate does not apply, and that vector<bool> should be unique among containers in accepting allocator<Anything>, then I believe that a normative sentence should be added to [vector.bool.pspc]/2, specifically creating an exemption to [container.alloc.reqmts]/5.