pipeline / debug: dump source folder content to check if version.py exists

.travis.yml

@@ -63,6 +63,7 @@ install:
   fi
 - pipenv graph
 - cat "$(pipenv --venv)"/lib/python*/site-packages/freesurfer-volume-reader.egg-link
+- (set -x; ls -la $TRAVIS_BUILD_DIR/freesurfer_volume_reader/)
 
 script:
 - pipenv run pylint freesurfer_volume_reader tests/*