pytest migration: move init_stack under TestControllerPytest Avoid top-level methods if they could be placed under classes. The init_stack method is only used from TestControllerPytest so it makes sense to scope it under that class.

# 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
.