shazow/urllib3 — pull request #411 by arkpog (2014-06-18 01:56:43+00:00)
Title: Allow _prepare_conn() to run on Python 2.6.4

When running on Python 2.6.4, a TypeError is thrown in _prepare_conn()
because httplib's _set_tunnel() only takes two parameters. This change
will let the code run on Python 2.6.4 if proxy_headers are not set.