Firefox Driver doesn't clean up /tmp/ profiles

[webtoman]

Meta -

OS: Ubuntu 16.04

Selenium Version: Standalone server 3.0.0 Beta 4

Browser: Firefox

Browser Version: 47.0.1

Expected Behavior -

No unused profile directories in anonymous*webdriver-profile

Actual Behavior -

Lots of unused profile directories. Eventually the VM running the selenium server ran out of disk space.

Steps to reproduce -

1. Start selenium server: java -jar selenium-server-standalone.jar
2. In Python, create and then quit a remote browser instance:

    from selenium import webdriver
    from selenium.webdriver.common.desired_capabilities import DesiredCapabilities.FIREFOX as ff

    driver = webdriver.Remote(command_executor='http://localhost:4444/wd/hub', desired_capabilities=ff)
    driver.quit()

1. Inspect the /tmp/ directory.
   ls -l /tmp/ | grep -E anonymous.*webdriver