ptr_map_adapter::insert leaks on exception

[olafvdspek@…]

If enforce_null_policy() throws, x is lost.

        std::pair<iterator,bool> insert_impl( const key_type& key, mapped_type x ) // strong
        {
            this->enforce_null_policy( x, "Null pointer in ptr_map_adapter::insert()" );
            auto_type ptr( x );                                         // nothrow

            std::pair<BOOST_DEDUCED_TYPENAME base_type::ptr_iterator,bool>
                 res = this->base().insert( std::make_pair( key, x ) ); // strong, commit      
            if( res.second )                                            // nothrow     
                ptr.release();                                          // nothrow
            return std::make_pair( iterator( res.first ), res.second ); // nothrow        
        }