When pip attempts to install the python-qpid-proton sdist, and the proton devel package has been installed, the installation fails.
setup.py finds that the necessary proton headers and library have been installed, so setup.py attempts to swig the installed headers. swig fails to find the headers and the install fails.
The failure is due to the setup.py not passing the correct -I search path to swig. It should pass the search path found by pkg-config