What steps will reproduce the problem?
1. Run the following in python:

from selenium import webdriver

profile = webdriver.FirefoxProfile("C:/firefox_profile_dir")
browser = webdriver.Firefox(firefox_profile=profile)

What is the expected output? What do you see instead?
Expect to see a new Firefox browser session started. Instead the following error is
returned:

  File "<stdin>", line 1, in <module>
  File "C:\Python27\lib\site-packages\selenium\webdriver\firefox\webdriver.py", line
61, in __init__
    self.binary, timeout),
  File "C:\Python27\lib\site-packages\selenium\webdriver\firefox\extension_connection.py",
line 47, in __init__
    self.binary.launch_browser(self.profile)
  File "C:\Python27\lib\site-packages\selenium\webdriver\firefox\firefox_binary.py",
line 50, in launch_browser
    self._start_from_profile_path(self.profile.path)
  File "C:\Python27\lib\site-packages\selenium\webdriver\firefox\firefox_binary.py",
line 73, in _start_from_profile_path
    env=self._firefox_env).communicate()
  File "C:\Python27\lib\subprocess.py", line 679, in __init__
    errread, errwrite)
  File "C:\Python27\lib\subprocess.py", line 893, in _execute_child
    startupinfo)
TypeError: environment can only contain strings


Looks like the issue stems from the Python 3 support added in 2.32, specifically the
line in firefox_profile.py:

from __future__ import unicode_literals


Selenium version: 2.32
OS: Windows 7 and XP
Browser: Firefox
Browser version: 17