pexpect.exitstatus not working?

[Adriaan Renting]

I'm doing something along these lines:

        """Check if the task is finished and clean up."""
        (pid, status) = os.waitpid(self._pid, os.WNOHANG) ## clean up the zombie
        assert(pid == self._pid)
        if os.WIFEXITED(status) or os.WIFSIGNALED(status):
            self._pid       = 0
            self.exitstatus = status
        assert(self.finished())
        del self._pid
        os.close(self._child_fd)
        os.close(self._errorpipe_end)
        ## Interpret the return value
        if (self.exitstatus == 0 or self.exitstatus > 255):
            if (self.exitstatus > 255):
                self.exitstatus = self.exitstatus >> 8
            else: self.exitstatus = 0