环境：
appium 1.4.13 chromedriver 2.18.343837 Mac 系统

问题
切换到 webview 后，查找元素失败后，会执行截图操作。但实际上，截图失败，并且测试脚本会 hang up, 要强制停止

测试用例脚本：

@user1hod_screen_args()
    def test_AA(self):
        invest_list =accountPage.Account(self.driver)
        username = login_cls[0][2]
        password = login_cls[0][3]
        logger.info('begin login app')
        invest_list.click_tab_me()
        loginButton = invest_list.is_element_exists(By.ID,u'com.yingzt.invest:id/summit_btn')
        if loginButton:
            login(self,username, password)
        else:
            pass
        invest_list.click_my_invest()
        sleep(2)
        context = self.driver.contexts
        self.driver.switch_to.context(u'WEBVIEW_com.yingzt.invest')
        invest_list.click_invest_list()
        sleep(2)
        hh = self.driver.window_handles
        sleep(2)
        self.driver.switch_to_window(hh[1])

invest_list.click_invest_contract() 这一步查找失败，触发截图

截屏装饰器

@staticmethod
    def staticmethod_screen_args(*wargs, **wkargs):
        def screen(func):
            @wraps(func)
            def wrapper(*args, **kwargs):
                try:
                    return func(*args, **kwargs)
                except:
                    saveScreen(MyDriver().get_driver(), func.__name__)
                    import sys
                    exc_info = sys.exc_info()
                    raise exc_info[0], None, exc_info[2]
            return wrapper
        return screen

def saveScreen(driver, name):
    time.sleep(1)
    now = time.strftime("%Y-%m-%d-%H_%M_%S", time.localtime(time.time()))
    pic_path = filepath+'/image/%s--%s.png' % (name, now)
    print u'截图保存路径为:\n%s' % os.path.abspath(pic_path)
    driver.get_screenshot_as_file(pic_path)

Appium 日志：