Jenkinsfile: run each py.test on a separate executor Running all py.test processes in parallel on the same executor is not a good idea. If a node has not much RAM, it could run out of memory when all py.test processes run at the same time. And If there are only 2 CPU cores, it doesn't make sense to run more then 2 processes either. Therefore use a separate executor for each one. The py.test processes will thus only run in parallel if there are multiple Jenkins executors available.

# requirements.txt file for use as "pip install -r requirements.txt" as a
# readthedocs compatible alternative to "pip install -e ." which is a working
# alternative to "setup.py develop" which doesn't work with Mercurial 3.7
.