this->get_Âallocator()== rhs.get_Âallocator() is true when
allocator_traits<Allocator>::propagate_on_container_move_assignment::value
is true; otherwise, the allocator is unchanged.
Preconditions: Either
allocator_Âtraits<Allocator>​::​propagate_Âon_Âcontainer_Âswap​::​value
is true
or
this->get_Âallocator()== other.get_Âallocator()
is true.