Vulture: allow empty arguments

apps/cli/executables/datafetcher/test/Dockerfile

-# datafetcher Dockerfile
-#
-# TO BUILD the docker image: -don't- "docker build" directly!
-# use docker_build.sh:
-# from apps/cli/executables/datafetcher,
-#
-#   ./docker_build.sh datafetcher_test[:N]
-#
-# where '-t' specifies a name and N' is the version.
-# (If ':N' is omitted, version is 'latest' by default.)
-# tag is not required for the build, but without it
-# the container name is an unhelpful hexadecimal value.
-
-FROM continuumio/miniconda3:latest
-
-COPY environment.yml .
-
-ENV PATH $HOME/miniconda3/bin/conda:$PATH
-
-# docker_build.sh should have copied environment.yml from data/;
-# it will be used in the command below
-RUN conda env update
-
-# get what we'll need for the build
-COPY . .
-
-# get application files and tests
-COPY src/ .
-COPY test/ .
-
-# install the application
-RUN ["conda", "run", "-n", "data", "python", "setup.py", "develop"]
-
-# we'll need a Capo profile
-ENV CAPO_PROFILE local
-ENV CAPO_PATH test/
-
-# finally, run the tests. be verbose. log stuff.
-# (for more detailed output, use "-vv" and/or "--log-level=DEBUG";
-#  to quit after first failure, use "-x")
- ENTRYPOINT ["conda", "run", "-n", "data", "pytest", "-vv", "--log-level=DEBUG", "--showlocals", "test/"]