Jupyter-core

[on GitHub](https://github.com/jupyter/jupyter_core/releases/tag/4.5.0)

- `jupyter --version` now tries to show the version number of various
other installed Jupyter packages, not just `jupyter_core`
([136](https://github.com/jupyter/jupyter_core/pull/136)). This will hopefully make
it clearer that there are various packages with their own version
numbers.
- Allow a `JUPYTER_CONFIG_PATH`
environment variable to specify a search path of additional
locations for config ([139](https://github.com/jupyter/jupyter_core/pull/139)).
- `jupyter subcommand` no longer modifies the `PATH` environment variable when it runs
`jupyter-subcommand` ([148](https://github.com/jupyter/jupyter_core/pull/148)).
- Jupyter's 'runtime' directory no longer uses `XDG_RUNTIME_DIR`
([143](https://github.com/jupyter/jupyter_core/pull/143)). While it has some
attractive properties, it has led to various problems; see the pull
request for details.
- Fix `JupyterApp` to respect the `raise_config_file_errors` traitlet
([149](https://github.com/jupyter/jupyter_core/pull/149)).
- Various improvements to the bash completion scripts in this
repository ([125](https://github.com/jupyter/jupyter_core/pull/125),
[126](https://github.com/jupyter/jupyter_core/pull/126)).
- The `setup.py` script now always uses setuptools, like most other
Jupyter projects ([147](https://github.com/jupyter/jupyter_core/pull/147)).
- The LICENSE file is included in wheels ([133](https://github.com/jupyter/jupyter_core/pull/133)).

[on GitHub](https://github.com/jupyter/jupyter_core/releases/tag/4.4.0)

- `jupyter troubleshoot` gets the list of packages from the Python
environment it's in, by using `sys.executable` to call `pip list`
([104](https://github.com/jupyter/jupyter_core/pull/104)).
- Added utility function `ensure_dir_exists`, and switched to using it
over the one from ipython_genutils, which does permissions wrong
([113](https://github.com/jupyter/jupyter_core/pull/113)).
- Avoid creating the `~/.ipython` directory when checking if it exists
for config migration ([118](https://github.com/jupyter/jupyter_core/pull/118)).
- Fix mistaken description in zsh completions ([98](https://github.com/jupyter/jupyter_core/pull/98)).
- Fix subcommand tests on Windows ([103](https://github.com/jupyter/jupyter_core/pull/103)).
- The README now describes how to work on `jupyter_core` and build the
docs ([110](https://github.com/jupyter/jupyter_core/pull/110)).
- Fix a broken link to a release in the docs ([109](https://github.com/jupyter/jupyter_core/pull/109)).

[on GitHub](https://github.com/jupyter/jupyter_core/releases/tag/4.3.0)

- Add `JUPYTER_NO_CONFIG` environment variable for
disabling all Jupyter configuration.
- More detailed error message when failing to launch subcommands.

[on GitHub](https://github.com/jupyter/jupyter_core/releases/tag/4.2.1)

- Fix error message on Windows when subcommand not found.
- Correctly display PATH in `jupyter troubleshoot` on Windows.