Python Selenium 2.48：等待最新版本的css崩溃

我为webdriver（Python）创建了以下扩展：

代码在2.47.3和2.48.0之间中断，我不知道为什么。 我正在使用FireFox驱动程序。如果我切换回2.47.3，它会再次正常工作

这是Django报告的结果

======================================================================
ERROR: test_changing_credentials (base.tests.test_base.BaseTest)
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Traceback (most recent call last):
File "/usr/lib/python2.7/unittest/case.py", line 329, in run testMethod()
File "/pipeline/source/django/base/tests/test_base.py", line 99, in   test_changing_credentials
driver.wait_for_css("h4#change-credentials-header").click()
File "/pipeline/source/django/libs/webdriver.py", line 45, in wait_for_css
raise TimeoutException(css_selector)
TimeoutException: Message: h4#change-credentials-header

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它要查找的元素在第一次尝试时不存在，但应在不到1秒的时间内出现。超时时间为7，因此应该可以工作。

中断了吗？怎样？请elaborate@e4c5：添加了报告的错误消息是否有隐式等待？

======================================================================
ERROR: test_changing_credentials (base.tests.test_base.BaseTest)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/usr/lib/python2.7/unittest/case.py", line 329, in run testMethod()
File "/pipeline/source/django/base/tests/test_base.py", line 99, in   test_changing_credentials
driver.wait_for_css("h4#change-credentials-header").click()
File "/pipeline/source/django/libs/webdriver.py", line 45, in wait_for_css
raise TimeoutException(css_selector)
TimeoutException: Message: h4#change-credentials-header