Selenium problems with code fail while performing browser.page_source

[James Cunningham]

Testing in two different python virtualenv and one system wide install
Selenium has the following problem. Selenium can browse to multiple test
sites with no problem but in each case fails with errors when performing

browser.page_source

Site browsing to: https://sec.gov

Browser: Firefox Quantum 61.0.1 64bit

Selenium version: 3.13.0 and 3.12.0

Web driver: v0.21.0 linux 64
  installed system wide at /usr/local/bin/geckodriver
  installed virtualenv at etlibs/bin/geckodriver
  installed virtualenv at etlibs/selenium/webdriver/firefox/amd64/geckodriver
 
OS: Ubuntu 16.04.04 LTS, codename: Xenial

Desktop: Mate 1.12.1

Problem:
Browses succesfuly each test to web site, for example https://sec.gov. But
the python program fails with errors each time while performing
browser.page_source

Code
########################################################################

    #!/usr/bin/env python
   
    import time
    from selenium import webdriver
   
    browser = webdriver.Firefox()
    browser.get('https://www.sec.gov/')
    time.sleep(15)
    this_html = browser.page_source
    print this_html

########################################################################

Error message when failing browser.page_source
########################################################################

james@james-Noir-et:~/Documents/no_env$ python test-selenium.py
Traceback (most recent call last):
  File "test-selenium.py", line 9, in <module>
    this_html = browser.page_source
  File "/home/james/.local/lib/python2.7/site-packages/selenium/webdriver/remote/webdriver.py", line 678, in page_source
    return self.execute(Command.GET_PAGE_SOURCE)['value']
  File "/home/james/.local/lib/python2.7/site-packages/selenium/webdriver/remote/webdriver.py", line 318, in execute
    response = self.command_executor.execute(driver_command, params)
  File "/home/james/.local/lib/python2.7/site-packages/selenium/webdriver/remote/remote_connection.py", line 472, in execute
    return self._request(command_info[0], url, body=data)
  File "/home/james/.local/lib/python2.7/site-packages/selenium/webdriver/remote/remote_connection.py", line 496, in _request
    resp = self._conn.getresponse()
  File "/usr/lib/python2.7/httplib.py", line 1136, in getresponse
    response.begin()
  File "/usr/lib/python2.7/httplib.py", line 453, in begin
    version, status, reason = self._read_status()
  File "/usr/lib/python2.7/httplib.py", line 417, in _read_status
    raise BadStatusLine(line)
httplib.BadStatusLine: ''
james@james-Noir-et:~/Documents/no_env$

########################################################################

I've tried a number of things except a different browser. Is anyone
have success using Firefox Quantum 61.0.1.64bit with Selenium browser.page_source?
Is this code OK?

Thanks in advance for any help.