Proposed resolution:

This wording is relative to N4986.

1. Modify [move.iterator] as indicated:

   namespace std {
     template<class Iterator>
     class move_iterator {
     public:
       […]
       constexpr move_iterator() requires default_initializable<Iterator> = default;
       […]
     private:
       Iterator current = Iterator();   // exposition only
     };
   }
   

2. Modify [move.iter.cons] as indicated:

   constexpr move_iterator();
   

   -1- Effects: Value-initializes current.