Fix test_exposition.py on Windows

[alexandrul]

No description provided.

[brian-brazil]

IIRC, this breaks in other OSes. Can you check this on Linux?

[alexandrul]

user@machine:/_apps/sentry/temp/client_python/tests$ ../../../python/bin/python --version
Python 2.7.9

user@machine:/_apps/sentry/temp/client_python/tests$ uname -a
Linux machine 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt20-1+deb8u3 (2016-01-17) x86_64 GNU/Linux

user@machine:/_apps/sentry/temp/client_python/tests$ cat test_exposition.py | grep local
        httpd = HTTPServer(('localhost', 0), TestHandler)

user@machine:/_apps/sentry/temp/client_python/tests$ ../../../python/bin/py.test
======== test session starts ========
platform linux2 -- Python 2.7.9 -- py-1.4.31 -- pytest-2.6.4
plugins: django
collected 68 items

test_core.py .................................
test_exposition.py ...............
test_parser.py ...............
test_process_collector.py ....
test_twisted.py s

======== 67 passed, 1 skipped in 0.23 seconds ========

[alexandrul]

On Windows I have Python 3.5.1 x64, and the previous output is from a Debian 8.