if oldState != http.StateActive {
					panic("invalid state transition")
				}
				s.conns[c] = cs
			}
			if s.closed {
				s.closeConn(c)
			}
		case http.StateHijacked, http.StateClosed:
			// Remove c from the set of tracked conns and decrement it from the
			// waitgroup, unless it was previously removed.
			if _, ok := s.conns[c]; ok {
				delete(s.conns, c)