Invalid Condition in BH controller

[Arash1381-y]

This section of code seems weird to me: (from bh_controller)

      if (!request_found) {
        // 2.2.1    We first check the priority buffer to prioritize e.g., maintenance requests
        if (m_priority_buffer.size() != 0) {
          req_buffer = &m_priority_buffer;
          req_it = m_priority_buffer.begin();
          req_it->command = m_dram->get_preq_command(req_it->final_command, req_it->addr_vec);
          
          request_found = m_dram->check_ready(req_it->command, req_it->addr_vec);
          if (!request_found & m_priority_buffer.size() != 0) {
            return false;
          }

        if (!request_found){
           ...

        }

the last condition is a bitwise operation of the request found boolean and the size of the priority buffer which does not change from the previous condition. what is the reason behind this bitwise operation?