deps =
    ...
    fasttest: python-djvulibre
    ...
    deeptest: python-djvulibre

13:41:10   Building wheel for python-djvulibre (PEP 517): started
13:41:10   Building wheel for python-djvulibre (PEP 517): finished with status 'error'
13:41:10   ERROR: Command errored out with exit status 1:
13:41:10    command: /src/.tox/fasttest-py35/bin/python /src/.tox/fasttest-py35/lib/python3.5/site-packages/pip/_vendor/pep517/_in_process.py build_wheel /tmp/tmp_1v9r5vf
13:41:10        cwd: /tmp/pip-install-g5jwgns0/python-djvulibre_ec128408a067445980b9ac988dbf0a6b
13:41:10   Complete output (12 lines):
13:41:10   running bdist_wheel
13:41:10   running build
13:41:10   running build_py
13:41:10   creating build
13:41:10   creating build/lib.linux-x86_64-3.5
13:41:10   creating build/lib.linux-x86_64-3.5/djvu
13:41:10   copying djvu/__init__.py -> build/lib.linux-x86_64-3.5/djvu
13:41:10   copying djvu/const.py -> build/lib.linux-x86_64-3.5/djvu
13:41:10   copying djvu/dllpath.py -> build/lib.linux-x86_64-3.5/djvu
13:41:10   running build_ext
13:41:10   cannot execute pkg-config: No such file or directory: 'pkg-config'
13:41:10   error: cannot determine DjVuLibre version
13:41:10   ----------------------------------------
13:41:10   ERROR: Failed building wheel for python-djvulibre
13:41:10 Successfully built pywikibot
13:41:10 Failed to build python-djvulibre
13:41:10 ERROR: Could not build wheels for python-djvulibre which use PEP 517 and cannot be installed directly