I have found that this issue is not in this Selenium version: 2.40.0 (and 2.30.0, 2.35.0,
etc)

I see one broken pipe left in version 2.40.0. But there was no broken pipe at all in
version 2.30.0. Is this relevant change?

After doing some git bisect, I found that the issue is introduced in "[8fc478b09ea3c76800d09ab6681f9c3895b1bbc4]
python switch_to_ deprecation / adding switch_to class like the other language bindings"

Ok, the situation is similar to this one.
http://ideone.com/u2rD92

A -> switch_to
B -> webdriver (in phantomjs module. it defined __del__)
C -> Popen object (it has __del__ by default)

This issue was closed by revision f6e1797dde53.

There is a problem with calling "stop()" from Service's "__del__()" method. From time
to time, we are getting:

 > Exception AttributeError: "'Service' object has no attribute 'process'" in <bound
method Service.__del__ of <selenium.webdriver.phantomjs.service.Service object at 0x7fbb28dc17d0>>
ignored

this happens in the "stop()" method where the service instance is not available anymore
(is None).

See more at relevant stackoverflow post: http://stackoverflow.com/questions/27674088/scrapy-with-selenium-webdriver-failing-to-instantiate.