Unexpected compile time error using requires clauses

Accelerated Computing CUDA CUDA NVCC Compiler
1

I’m pretty sure I’ve stumled across a bug in the concepts implementation of nvcc:

template <typename T>
struct S
{
    T t;

    template <typename U>
    requires (false)
    S& operator=(U&& t){
        t.a();
        return *this;
    }
};

template <typename T>
struct S2 : S<T>
{
    using S<T>::operator=;
};

int main()
{
    int a;
    S2<int&> s{a};

}

This results in the following error (Godbolt link):

<source>(15): error: template constraint not satisfied
<source>(7): note #3135-D: substitution of arguments "<S<int &>>" for requires-clause failed
<source>(7): note #3043-D: atomic constraint evaluates to false
          detected during instantiation of class "S2<T> [with T=int &]" 
(23): here

1 error detected in the compilation of "<source>".
Compiler returned: 2

The same does not happen in clang or gcc, and also only happens when using reference types & the using ...::operator=; declaration - I assume this is a bug in nvcc? Any easy workarounds apart from falling back to SFINAE with std::enable_if_t?