title: python error:ImportError: sys.meta_path is None, Python is likely shutting down
body: <p>I write a python program in pycharm,including FBCrawl.py,html_login.py,common/glovar.py,in glovar.py, I define a variable webdriver_browser, and want use this webdriver_browser in FBCrawl.py AND html_login.py,the main purpose is to log in facebook and get content of a page,using selenium,the program are as follows, but when running it, 
  <strong>it errors:</strong></p>
  
  <pre><code>C:\Python\Python36\python.exe           C:/Python/PyCharmProject/FaceBookCrawl/FBCrawl.py
  None
  Exception ignored in: &lt;bound method Service.__del__ of &lt;selenium.webdriver.chrome.service.Service object at 0x00000146BF1FD438&gt;&gt;
  Traceback (most recent call last):
    File "C:\Python\Python36\lib\site-packages\selenium\webdriver\common\service.py", line 173, in __del__
    File "C:\Python\Python36\lib\site-packages\selenium\webdriver\common\service.py", line 149, in stop
    File "C:\Python\Python36\lib\site-packages\selenium\webdriver\common\service.py", line 120, in send_remote_shutdown_command
   ImportError: sys.meta_path is None, Python is likely shutting down
  
   Process finished with exit code 0
  </code></pre>
  
  <p><strong>The program are here:</strong></p>
  
  <p>FBCrwal.py:</p>
  
  <pre><code>from common import glovar
  from html_login import HtmlLogin
  from selenium import webdriver
  
  if __name__ == '__main__':
  
      baseurl = "http://www.google.com"
      #log in the website
      login_url = "https://www.facebook.com/login.php?login_attempt=1&amp;lwv=110"
      HtmlLogin().login(login_url)
      html_cont = glovar.webdriver_browser.get("https://www.facebook.com/alexis.n.griffith.3")
      print(html_cont)
  </code></pre>
  
  <p>html_login.py:</p>
  
  <pre><code>from selenium import webdriver
  
  from common import glovar
  
  
  class HtmlLogin(object):
  
      def login(self,url):
          if url is None:
              return
          login_url = url
          glovar.webdriver_browser = webdriver.Chrome()
          glovar.webdriver_browser.get(login_url)
          #user credentials
          user =  glovar.webdriver_browser.find_element_by_css_selector("#email")
          user.send_keys('********@gmail.com')
          password = glovar.webdriver_browser.find_element_by_css_selector("#pass")
          password.send_keys('********')
          login = glovar.webdriver_browser.find_element_by_css_selector("#loginbutton")
          login.click()
  </code></pre>
  
  <p>glovar.py:</p>
  
  <pre><code>webdriver_browser =  None
  </code></pre>
  
  <p>could you please tell me the reason and how to solve it</p>