Python 3.6 issue, tests segfault

[perrygeo]

Hoping to get python 3.6 support going today but ran into a curious blocker - Tests immediately segfault.

⭆ mkvirtualenv -p python3.6 rasterstats36
⭆ python --version
Python 3.6.1
⭆ pip install --pre 'rasterio>=1.0a7'  # Also tried with master and src_dist build of 0.36
⭆ pip install -r requirements_dev.txt
⭆ pip install -e .
⭆ py.test -v
====================================================== test session starts ======================================================
platform darwin -- Python 3.6.1, pytest-3.0.7, py-1.4.33, pluggy-0.4.0 -- /Users/mperry/env/rasterstats36/bin/python3.6
cachedir: .cache
rootdir: /Users/mperry/projects/python-rasterstats, inifile: setup.cfg
plugins: cov-2.4.0
collecting 0 itemsSegmentation fault: 11

Same procedure passes 👌 on python 3.5.2.