this may be fixed on 2.0.4 but not 2.0.8? https://groups.google.com/forum/#!topic/librets/uN0UKRO7juE

try setting CC in the environment for clang+bindings builds to get travis to actually use clang for them

Python 2.6 is unsupported because the PyCapsule API was backported from Python 3 to 2.7. Trying Python 3.3 and 3.2 just for grins.