我正在尝试遵循有关Selenium的教程http://selenium-python.readthedocs.io/getting-
started.html。我已下载的最新版本geckodriver并将其复制到/usr/local/bin。但是，当我尝试

from selenium import webdriver
driver = webdriver.Firefox()

我收到以下错误消息：

Traceback (most recent call last):
  File "/Users/kurtpeek/Documents/Scratch/selenium_getting_started.py", line 4, in <module>
    driver = webdriver.Firefox()
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/selenium/webdriver/firefox/webdriver.py", line 152, in __init__
    keep_alive=True)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/selenium/webdriver/remote/webdriver.py", line 98, in __init__
    self.start_session(desired_capabilities, browser_profile)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/selenium/webdriver/remote/webdriver.py", line 188, in start_session
    response = self.execute(Command.NEW_SESSION, parameters)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/selenium/webdriver/remote/webdriver.py", line 252, in execute
    self.error_handler.check_response(response)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/selenium/webdriver/remote/errorhandler.py", line 194, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.WebDriverException: Message: Unable to find a matching set of capabilities

[Finished in 1.2s with exit code 1]

从https://github.com/SeleniumHQ/selenium/issues/3884看来，其他用户也遇到了类似的问题，但是Selenium团队无法复制它。如何使Selenium与Firefox兼容？（它确实可以chromedriver和一个webdriver.Chrome()实例一起使用，所以我怀疑这可能是Selenium中的错误）。