Building python packages that have C modules fails with snapcraft as C headers are not found. This is a sample snap that fails building on Bionic: name: test version: '1.0' summary: test description: test grade: stable confinement: strict base: core18 apps:   uwsgi:     command: uwsgi parts:   uwsgi:     plugin: python     source: .     python-packages:       - uWSGI     build-packages:       - python3-dev     stage-packages:       - libpython3.6 exporting C_INCLUDE_PATH=/usr/include/python3.6 makes it work. Tested with both stable (2.43.1) and candidate (3.0) snaps. Also, removing the core18 base and using libpython3.5 when building on xenial shows the same issue