[igraph] install trouble

[Mad Tinker]

I've installed igraph on older Macs many times, but seem to having a
particular bit of trouble this time. Here is some background:

Configuration:
--OS X 10.11.6 Captain
-- Python 2.7 (location: /Library/Python/2.7 )

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from page: http://igraph.org/python/doc/tutorial/install.html
--- Tried to use OS X binary installer, but installation failed

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from http://igraph.org/c/
-- download/install C-core
% ./configure
% make
% make install

Next --------------------
% easy_install python-igraph
Searching for python-igraph
Reading https://pypi.python.org/simple/python-igraph/
Best match: python-igraph 0.7.1.post6
Downloading
https://pypi.python.org/packages/0f/a0/4e7134f803737aa6eebb4e5250565ace0e2599659e22be7f7eba520ff017/python-igraph-0.7.1.post6.tar.gz#md5=a4c0b5960735b36adb5d3a40031cb7c0
Processing python-igraph-0.7.1.post6.tar.gz
Writing
/var/folders/d8/m2pf957d6ggc9s8yycvc2wsm0000gp/T/easy_install-zmpkEv/python-igraph-0.7.1.post6/setup.cfg
Running python-igraph-0.7.1.post6/setup.py -q bdist_egg --dist-dir
/var/folders/d8/m2pf957d6ggc9s8yycvc2wsm0000gp/T/easy_install-zmpkEv/python-igraph-0.7.1.post6/egg-dist-tmp-NsmNx7
Cannot find the C core of igraph on this system using pkg-config.
We will now try to download and compile the C core from scratch.
Version number of the C core: 0.7.1.post6
We will also try: 0.7.1

Version 0.7.1.post6 of the C core of igraph is not found among the nightly
builds.
Use the --c-core-version switch to try a different version.

Could not download and compile the C core of igraph.

error: Setup script exited with 1

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Any insight into what I may be doing wrong?

Thanks in advance,
Dave Robinson