Pin pip and pipenv versions for now

pipenv is broken by:

pypa/pipenv#2956

.travis.yml

@@ -6,15 +6,16 @@ cache:
  - $HOME/.cache/pip
  - .arca/cache
 install:
-- python -m pip install pipenv --upgrade
+- python -m pip install --upgrade 'pip<18.1' 'pipenv<2018.10.7'
+- pipenv install 'git+https://github.com/pyvec/arca.git@pip_pipenv#egg=arca' 'docker~=3.2.1'
 - pipenv install --deploy --dev
 before_script: # encrypted variables aren't accessible in PRs
 - 'if [ -n "$DOCKER_HUB_PASSWORD" ]; then docker login -u "$DOCKER_HUB_USERNAME" -p "$DOCKER_HUB_PASSWORD"; fi'
 - 'if [ -z "$DOCKER_HUB_PASSWORD" ]; then export ARCA_BACKEND_REGISTRY_PULL_ONLY=true; fi'
 script:
 - pipenv graph
 - pipenv run test
-- pipenv run naucse list_courses # don't remove, there might be timeouts otherwise, see naucse/cli.py for details
+- pipenv run naucse list-courses # don't remove, there might be timeouts otherwise, see naucse/cli.py for details
 - pipenv run naucse freeze --verbose
 after_script:
 - echo "Suplementary logs:"