Log Message:
py-tox: updated to 3.4.0

3.4.0:

Bugfixes
- add --exists-action w to default pip flags to handle better VCS dependencies
- instead of assuming the Python version from the base python name ask the \ 
interpreter to reveal the version for the ignore_basepython_conflict flag
- PEP-517 packaging fails with sdist already exists, fixed via ensuring the dist \ 
folder is empty before invoking the backend and pypa/setuptools

Features
- add commands_pre and commands_post that run before and after running
  the commands (setup runs always, commands only if setup suceeds, teardown \ 
always - all
  run until the first failing command)
- pyproject.toml config support initially by just inline the tox.ini under \ 
tool.tox.legacy_tox_ini key; config source priority order is pyproject.toml, \ 
tox.ini and then setup.cfg
- use the os environment variable TOX_SKIP_ENV to filter out tox environment \ 
names from the run list (set by envlist)
- always set PIP_USER=0 (do not install into the user site package, but inside \ 
the virtual environment created) and PIP_NO_DEPS=0 (installing without \ 
dependencies can cause broken package installations) inside tox
- tox will inject some environment variables that to indicate a command is \ 
running within tox: TOX_WORK_DIR env var is set to the tox work directory,
  TOX_ENV_NAME is set to the current running tox environment name, TOX_ENV_DIR \ 
is set to the current tox environments working dir
- While running tox invokes various commands (such as building the package, pip \ 
installing dependencies and so on), these were printed in case they failed as \ 
Python arrays. Changed the representation to a shell command, allowing the users \ 
to quickly replicate/debug the failure on their own
- skip missing interpreters value from the config file can now be overridden via \ 
the --skip-missing-interpreters cli flag
- keep additional environments config order when listing them
- allow injecting config value inside the ini file dependent of the fact that \ 
we're connected to an interactive shell or not
- do not build sdist if skip install is specified for the envs to be run
- when verbosity level increases above two start passing through verbosity flags \ 
to pip
- when discovering the interpreter to use check if the tox host Python matches \ 
and use that if so
- -vv will print out why a virtual environment is re-created whenever this \ 
operation is triggered

Documentation
- clarify that python and pip refer to the virtual environments executable
- add Sphinx and mkdocs example of generating documentation via tox
- specify that setup.cfg tox configuration needs to be inside the tox:tox namespace

3.3.0:

Bugfixes
- fix TOX_LIMITED_SHEBANG when running under python3

Features
- PEP-517 <https://www.python.org/dev/peps/pep-0517/>_ source distribution \ 
support (create a
  .package virtual environment to perform build operations inside)
- flit <https://flit.readthedocs.io>_ support via implementing PEP-517
- packaging now is exposed as a hook via tox_package(session, venv)

Miscellaneous
- Updated the VSTS build YAML to use the latest jobs and pools syntax