Remove assertion that used moved allocator. Fixes #10777.

doc/changes.qbk

@@ -263,5 +263,7 @@ C++11 support has resulted in some breaking changes:
 * Remove unnecessary template parameter from const iterators.
 * Rename private `iterator` typedef in some iterator classes, as it
   confuses some traits classes.
+* Fix move assignment with stateful, propagate_on_container_move_assign
+  allocators ([ticket 10777]).
 
 [endsect]

include/boost/unordered/detail/table.hpp

@@ -500,9 +500,11 @@ namespace boost { namespace unordered { namespace detail {
             op2.commit();
         }
 
+        // Only call with nodes allocated with the currect allocator, or
+        // one that is equal to it. (Can't assert because other's
+        // allocators might have already been moved).
         void move_buckets_from(table& other)
         {
-            BOOST_ASSERT(node_alloc() == other.node_alloc());
             BOOST_ASSERT(!buckets_);
             buckets_ = other.buckets_;
             bucket_count_ = other.bucket_count_;