namespace A
{
    namespace B.C
    {
        
    }
}

Put the caret onto 'C' and rename in to 'A.B.D'

namespace A
{
    namespace B
    {
        namespace A.B.D
        {
        
        }
    }
}

Expected:

namespace A
{
    namespace B.D
    {
        
    }
}

Issue was closed