./tests/helpers/.
pytest>=3.0 ; python_version > "2.6"
pytest==3.2 ; python_version == "2.6"

./tests/helpers/.
pytest>=3.3 ; python_version == "2.7" or python_version >= "3.5"
pytest==3.2 ; python_version == "2.6" or python_version == "3.4"

Correct py.test pinned version for Python 3.4
Correct py.test pinned version for Python 3.4
