Wait for the subprocess to finish.

        Returns the exit code.

def wait(self):
        '''Wait for the subprocess to finish.

        Returns the exit code.
        '''
        status = self.proc.wait()
        if status >= 0:
            self.exitstatus = status
            self.signalstatus = None
        else:
            self.exitstatus = None
            self.signalstatus = -status
        self.terminated = True
        return status