tox -e py33 instead of failing uses python 3.7

[mgedmin]

I was dusting off a slightly older project of mine that had envlist = py27,py33,py34,py35,py36,py37 in its tox.ini.

Imagine my surprise when tox said all the environments except py34 were successfull. I don't have Python 3.4 on my machine, since it's EOL, but I also don't have Python 3.3, so how did it work?

Imagine my surprise when .tox/py33/bin/python --version said Python 3.7.3.

Details:

$ git clone https://github.com/mgedmin/ghcloneall
$ cd ghcloneall
$ tox -re py33 --notest -vv
using tox.ini: /home/mg/src/ghcloneall/tox.ini (pid 20653)
  removing /home/mg/src/ghcloneall/.tox/log
using tox-3.13.2 from /home/mg/.local/pipx/venvs/tox/lib/python3.7/site-packages/tox/__init__.py (pid 20653)
GLOB start: packaging 
GLOB sdist-make: /home/mg/src/ghcloneall/setup.py
  removing /home/mg/src/ghcloneall/.tox/dist
[20659] /home/mg/src/ghcloneall$ /home/mg/.local/pipx/venvs/tox/bin/python setup.py sdist --formats=zip --dist-dir .tox/dist >.tox/log/GLOB-0.log
running sdist
running egg_info
writing ghcloneall.egg-info/PKG-INFO
writing dependency_links to ghcloneall.egg-info/dependency_links.txt
writing entry points to ghcloneall.egg-info/entry_points.txt
writing requirements to ghcloneall.egg-info/requires.txt
writing top-level names to ghcloneall.egg-info/top_level.txt
reading manifest file 'ghcloneall.egg-info/SOURCES.txt'
reading manifest template 'MANIFEST.in'
writing manifest file 'ghcloneall.egg-info/SOURCES.txt'
running check
creating ghcloneall-1.7.1.dev0
creating ghcloneall-1.7.1.dev0/ghcloneall.egg-info
copying files to ghcloneall-1.7.1.dev0...
copying CHANGES.rst -> ghcloneall-1.7.1.dev0
copying LICENCE -> ghcloneall-1.7.1.dev0
copying MANIFEST.in -> ghcloneall-1.7.1.dev0
copying README.rst -> ghcloneall-1.7.1.dev0
copying ghcloneall.py -> ghcloneall-1.7.1.dev0
copying setup.cfg -> ghcloneall-1.7.1.dev0
copying setup.py -> ghcloneall-1.7.1.dev0
copying tox.ini -> ghcloneall-1.7.1.dev0
copying ghcloneall.egg-info/PKG-INFO -> ghcloneall-1.7.1.dev0/ghcloneall.egg-info
copying ghcloneall.egg-info/SOURCES.txt -> ghcloneall-1.7.1.dev0/ghcloneall.egg-info
copying ghcloneall.egg-info/dependency_links.txt -> ghcloneall-1.7.1.dev0/ghcloneall.egg-info
copying ghcloneall.egg-info/entry_points.txt -> ghcloneall-1.7.1.dev0/ghcloneall.egg-info
copying ghcloneall.egg-info/not-zip-safe -> ghcloneall-1.7.1.dev0/ghcloneall.egg-info
copying ghcloneall.egg-info/requires.txt -> ghcloneall-1.7.1.dev0/ghcloneall.egg-info
copying ghcloneall.egg-info/top_level.txt -> ghcloneall-1.7.1.dev0/ghcloneall.egg-info
Writing ghcloneall-1.7.1.dev0/setup.cfg
creating '.tox/dist/ghcloneall-1.7.1.dev0.zip' and adding 'ghcloneall-1.7.1.dev0' to it
adding 'ghcloneall-1.7.1.dev0'
adding 'ghcloneall-1.7.1.dev0/ghcloneall.egg-info'
adding 'ghcloneall-1.7.1.dev0/ghcloneall.py'
adding 'ghcloneall-1.7.1.dev0/setup.cfg'
adding 'ghcloneall-1.7.1.dev0/README.rst'
adding 'ghcloneall-1.7.1.dev0/CHANGES.rst'
adding 'ghcloneall-1.7.1.dev0/MANIFEST.in'
adding 'ghcloneall-1.7.1.dev0/setup.py'
adding 'ghcloneall-1.7.1.dev0/PKG-INFO'
adding 'ghcloneall-1.7.1.dev0/LICENCE'
adding 'ghcloneall-1.7.1.dev0/tox.ini'
adding 'ghcloneall-1.7.1.dev0/ghcloneall.egg-info/requires.txt'
adding 'ghcloneall-1.7.1.dev0/ghcloneall.egg-info/not-zip-safe'
adding 'ghcloneall-1.7.1.dev0/ghcloneall.egg-info/entry_points.txt'
adding 'ghcloneall-1.7.1.dev0/ghcloneall.egg-info/dependency_links.txt'
adding 'ghcloneall-1.7.1.dev0/ghcloneall.egg-info/PKG-INFO'
adding 'ghcloneall-1.7.1.dev0/ghcloneall.egg-info/SOURCES.txt'
adding 'ghcloneall-1.7.1.dev0/ghcloneall.egg-info/top_level.txt'
removing 'ghcloneall-1.7.1.dev0' (and everything under it)

GLOB finish: packaging  after 0.16 seconds
copying new sdistfile to '/home/mg/.tox/distshare/ghcloneall-1.7.1.dev0.zip'
package .tmp/package/1/ghcloneall-1.7.1.dev0.zip links to dist/ghcloneall-1.7.1.dev0.zip (/home/mg/src/ghcloneall/.tox)
py33 start: getenv /home/mg/src/ghcloneall/.tox/py33
py33 cannot reuse: -r flag
py33 recreate: /home/mg/src/ghcloneall/.tox/py33
/home/mg/.local/pipx/venvs/tox/bin/python (/home/mg/.local/pipx/venvs/tox/bin/python) is {'executable': '/home/mg/.local/pipx/venvs/tox/bin/python', 'name': 'python', 'version_info': [3, 7, 3, 'final', 0], 'version': '3.7.3 (default, Apr  3 2019, 05:39:12) \n[GCC 8.3.0]', 'is_64': True, 'sysplatform': 'linux'}
py33 uses /home/mg/.local/pipx/venvs/tox/bin/python
  removing /home/mg/src/ghcloneall/.tox/py33
setting PATH=/home/mg/src/ghcloneall/.tox/py33/bin:/home/mg/bin:/home/mg/bin/local:/home/mg/.venv/bin:/home/mg/.local/bin:/home/mg/.cargo/bin:/usr/lib/ccache:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/snap/bin:/var/lib/snapd/snap/bin
[20664] /home/mg/src/ghcloneall/.tox$ /home/mg/.local/pipx/venvs/tox/bin/python -m virtualenv --no-download --python /home/mg/.local/pipx/venvs/tox/bin/python py33
Already using interpreter /home/mg/.local/pipx/venvs/tox/bin/python
Using base prefix '/usr'
New python executable in /home/mg/src/ghcloneall/.tox/py33/bin/python
Installing setuptools, pip, wheel...
done.
py33 finish: getenv /home/mg/src/ghcloneall/.tox/py33 after 2.73 seconds
py33 start: installpkg /home/mg/src/ghcloneall/.tox/.tmp/package/1/ghcloneall-1.7.1.dev0.zip
py33 inst: /home/mg/src/ghcloneall/.tox/.tmp/package/1/ghcloneall-1.7.1.dev0.zip
write config to /home/mg/src/ghcloneall/.tox/py33/.tox-config1 as '967e4202bf8f26c8d31271cb2e2f12ac /home/mg/.local/pipx/venvs/tox/bin/python\n3.13.2 0 0 0'
setting PATH=/home/mg/src/ghcloneall/.tox/py33/bin:/home/mg/bin:/home/mg/bin/local:/home/mg/.venv/bin:/home/mg/.local/bin:/home/mg/.cargo/bin:/usr/lib/ccache:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/snap/bin:/var/lib/snapd/snap/bin
[20675] /home/mg/src/ghcloneall$ /home/mg/src/ghcloneall/.tox/py33/bin/python -m pip install --exists-action w .tox/.tmp/package/1/ghcloneall-1.7.1.dev0.zip
Processing ./.tox/.tmp/package/1/ghcloneall-1.7.1.dev0.zip
Collecting requests (from ghcloneall==1.7.1.dev0)
  Using cached https://files.pythonhosted.org/packages/51/bd/23c926cd341ea6b7dd0b2a00aba99ae0f828be89d72b2190f27c11d4b7fb/requests-2.22.0-py2.py3-none-any.whl
Collecting requests_cache (from ghcloneall==1.7.1.dev0)
  Using cached https://files.pythonhosted.org/packages/15/d1/6b9836a781d18811d7f0ca7731d0ee817c4e6f33b7ecd8502ad20996b3e9/requests_cache-0.5.0-py2.py3-none-any.whl
Collecting idna<2.9,>=2.5 (from requests->ghcloneall==1.7.1.dev0)
  Using cached https://files.pythonhosted.org/packages/14/2c/cd551d81dbe15200be1cf41cd03869a46fe7226e7450af7a6545bfc474c9/idna-2.8-py2.py3-none-any.whl
Collecting urllib3!=1.25.0,!=1.25.1,<1.26,>=1.21.1 (from requests->ghcloneall==1.7.1.dev0)
  Using cached https://files.pythonhosted.org/packages/e6/60/247f23a7121ae632d62811ba7f273d0e58972d75e58a94d329d51550a47d/urllib3-1.25.3-py2.py3-none-any.whl
Collecting certifi>=2017.4.17 (from requests->ghcloneall==1.7.1.dev0)
  Using cached https://files.pythonhosted.org/packages/69/1b/b853c7a9d4f6a6d00749e94eb6f3a041e342a885b87340b79c1ef73e3a78/certifi-2019.6.16-py2.py3-none-any.whl
Collecting chardet<3.1.0,>=3.0.2 (from requests->ghcloneall==1.7.1.dev0)
  Using cached https://files.pythonhosted.org/packages/bc/a9/01ffebfb562e4274b6487b4bb1ddec7ca55ec7510b22e4c51f14098443b8/chardet-3.0.4-py2.py3-none-any.whl
Building wheels for collected packages: ghcloneall
  Building wheel for ghcloneall (setup.py) ... done
  Stored in directory: /home/mg/.cache/pip/wheels/7d/c2/1b/8efad63d6a3e6f71025463e3f98e3d939604c3ca3dff992270
Successfully built ghcloneall
Installing collected packages: idna, urllib3, certifi, chardet, requests, requests-cache, ghcloneall
  Found existing installation: ghcloneall 1.7.1.dev0
    Not uninstalling ghcloneall at /home/mg/src/ghcloneall, outside environment /home/mg/src/ghcloneall/.tox/py33
    Can't uninstall 'ghcloneall'. No files were found to uninstall.
Successfully installed certifi-2019.6.16 chardet-3.0.4 ghcloneall-1.7.1.dev0 idna-2.8 requests-2.22.0 requests-cache-0.5.0 urllib3-1.25.3
WARNING: You are using pip version 19.1.1, however version 19.2.2 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
py33 finish: installpkg /home/mg/src/ghcloneall/.tox/.tmp/package/1/ghcloneall-1.7.1.dev0.zip after 1.59 seconds
py33 start: envreport 
setting PATH=/home/mg/src/ghcloneall/.tox/py33/bin:/home/mg/bin:/home/mg/bin/local:/home/mg/.venv/bin:/home/mg/.local/bin:/home/mg/.cargo/bin:/usr/lib/ccache:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/snap/bin:/var/lib/snapd/snap/bin
[20687] /home/mg/src/ghcloneall$ /home/mg/src/ghcloneall/.tox/py33/bin/python -m pip freeze >.tox/py33/log/py33-0.log
py33 finish: envreport  after 0.23 seconds
py33 installed: certifi==2019.6.16,chardet==3.0.4,ghcloneall==1.7.1.dev0,idna==2.8,requests==2.22.0,requests-cache==0.5.0,urllib3==1.25.3
_________________________________________________________________ summary __________________________________________________________________
  py33: skipped tests
  congratulations :)
cleanup /home/mg/src/ghcloneall/.tox/.tmp/package/1/ghcloneall-1.7.1.dev0.zip

[asottile]

this is fixed on master, there was a regression recently

see #1377