text: Title: Tox 4 trying to reuse env where it didn't in tox 3
  Body: ## Issue
  
  Given this config:
  ```ini
  [testenv:black]
  deps =
      black==23.3.0
  commands = {envpython} -m black . --check
  
  [testenv:tip-black]
  deps = black
  commands = {[testenv:black]commands}
  ```
  
  in tox 3.28.0, both executions (via `tox -e <env>`) worked and ran in different environments. We'd get the following line in the output from the `black` env:
  ```
  black run-test: commands[0] | /home/james/c/tox_test/.tox/black/bin/python -m black . --check
  ```
  vs the following in the `tip-black` env:
  ```
  tip-black run-test: commands[0] | /home/james/c/tox_test/.tox/tip-black/bin/python -m black . --check
  ```
  Notice the path differences.
  
  However, in tox 4.6.4, I get this for `black`:
  ```
  black: commands[0]> .tox/black/bin/python -m black . --check
  ```
  and an error for `tip-black`:
  ```
  tip-black: commands[0]> .tox/black/bin/python -m black . --check
  tip-black: failed with /home/james/c/tox_test/.tox/black/bin/python (resolves to /home/james/c/tox_test/.tox/black/bin/python) is not allowed, use allowlist_externals to allow it
  ```
  
  Why is it trying to reuse the `black` environment for `tip-black`? It didn't do that in tox 3.
  
  ## Environment
  
  - OS: Ubuntu 23.04
  
  ## Full outputs
  tox 3.28.0, `black` env:
  ```console
  GLOB sdist-make: /home/james/c/tox_test/setup.py
  black inst-nodeps: /home/james/c/tox_test/.tox/.tmp/package/1/UNKNOWN-0.0.0.zip
  black installed: black==23.3.0,click==8.1.6,importlib-metadata==6.7.0,mypy-extensions==1.0.0,packaging==23.1,pathspec==0.11.2,platformdirs==3.10.0,tomli==2.0.1,typed-ast==1.5.5,typing_extensions==4.7.1,UNKNOWN @ file:///home/james/c/tox_test/.tox/.tmp/package/1/UNKNOWN-0.0.0.zip,zipp==3.15.0
  black run-test-pre: PYTHONHASHSEED='772606141'
  black run-test: commands[0] | /home/james/c/tox_test/.tox/black/bin/python -m black . --check
  All done! ✨ 🍰 ✨
  1 file would be left unchanged.
  ___________________________________ summary ____________________________________
    black: commands succeeded
    congratulations :)
  ```
  tox 3.28.0, `tip-black` env:
  ```console
  GLOB sdist-make: /home/james/c/tox_test/setup.py
  tip-black create: /home/james/c/tox_test/.tox/tip-black
  tip-black installdeps: black
  tip-black inst: /home/james/c/tox_test/.tox/.tmp/package/1/UNKNOWN-0.0.0.zip
  tip-black installed: black==23.3.0,click==8.1.6,importlib-metadata==6.7.0,mypy-extensions==1.0.0,packaging==23.1,pathspec==0.11.2,platformdirs==3.10.0,tomli==2.0.1,typed-ast==1.5.5,typing_extensions==4.7.1,UNKNOWN @ file:///home/james/c/tox_test/.tox/.tmp/package/1/UNKNOWN-0.0.0.zip,zipp==3.15.0
  tip-black run-test-pre: PYTHONHASHSEED='1485184410'
  tip-black run-test: commands[0] | /home/james/c/tox_test/.tox/tip-black/bin/python -m black . --check
  All done! ✨ 🍰 ✨
  1 file would be left unchanged.
  ___________________________________ summary ____________________________________
    tip-black: commands succeeded
    congratulations :)
  ```
  tox 4.6.4, `black` env:
  ```console
  black: install_deps> python -I -m pip install black==23.3.0
  .pkg: install_requires> python -I -m pip install 'setuptools>=40.8.0' wheel
  .pkg: _optional_hooks> python /home/james/.pyenv/versions/3.7.16/envs/cloud-init37/lib/python3.7/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
  .pkg: get_requires_for_build_sdist> python /home/james/.pyenv/versions/3.7.16/envs/cloud-init37/lib/python3.7/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
  .pkg: get_requires_for_build_wheel> python /home/james/.pyenv/versions/3.7.16/envs/cloud-init37/lib/python3.7/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
  .pkg: install_requires_for_build_wheel> python -I -m pip install wheel
  .pkg: prepare_metadata_for_build_wheel> python /home/james/.pyenv/versions/3.7.16/envs/cloud-init37/lib/python3.7/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
  .pkg: build_sdist> python /home/james/.pyenv/versions/3.7.16/envs/cloud-init37/lib/python3.7/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
  black: install_package> python -I -m pip install --force-reinstall --no-deps /home/james/c/tox_test/.tox/.tmp/package/1/UNKNOWN-0.0.0.tar.gz
  black: commands[0]> .tox/black/bin/python -m black . --check
  .pkg: _exit> python /home/james/.pyenv/versions/3.7.16/envs/cloud-init37/lib/python3.7/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
    black: OK (2.56=setup[2.49]+cmd[0.07] seconds)
    congratulations :) (2.60 seconds)
  ```
  tox 4.6.4, `tip-black` env:
  ```console
  tip-black: install_deps> python -I -m pip install black
  .pkg: _optional_hooks> python /home/james/.pyenv/versions/3.7.16/envs/cloud-init37/lib/python3.7/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
  .pkg: get_requires_for_build_sdist> python /home/james/.pyenv/versions/3.7.16/envs/cloud-init37/lib/python3.7/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
  .pkg: get_requires_for_build_wheel> python /home/james/.pyenv/versions/3.7.16/envs/cloud-init37/lib/python3.7/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
  .pkg: prepare_metadata_for_build_wheel> python /home/james/.pyenv/versions/3.7.16/envs/cloud-init37/lib/python3.7/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
  .pkg: build_sdist> python /home/james/.pyenv/versions/3.7.16/envs/cloud-init37/lib/python3.7/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
  tip-black: install_package> python -I -m pip install --force-reinstall --no-deps /home/james/c/tox_test/.tox/.tmp/package/2/UNKNOWN-0.0.0.tar.gz
  tip-black: commands[0]> .tox/black/bin/python -m black . --check
  tip-black: failed with /home/james/c/tox_test/.tox/black/bin/python (resolves to /home/james/c/tox_test/.tox/black/bin/python) is not allowed, use allowlist_externals to allow it
  .pkg: _exit> python /home/james/.pyenv/versions/3.7.16/envs/cloud-init37/lib/python3.7/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
    tip-black: FAIL code 1 (1.39 seconds)
    evaluation failed :( (1.43 seconds)
  ```