Allocator concept requires copy assignment.

include/boost/container/allocator.hpp

@@ -113,9 +113,6 @@ class allocator
    template<class T2, unsigned int Version2, unsigned int AllocationDisableMask2>
    allocator& operator=(const allocator<T2, Version2, AllocationDisableMask2>&);
 
-   //Not assignable from other allocator
-   allocator& operator=(const allocator&);
-
    static const unsigned int ForbiddenMask =
       BOOST_CONTAINER_ALLOCATE_NEW | BOOST_CONTAINER_EXPAND_BWD | BOOST_CONTAINER_EXPAND_FWD ;