Bash version detection fails with certain locales

[janLo]

I have a machine where the system locale is set to de_DE.UTF-8. The output of bash --version here is:

GNU bash, Version 5.1.4(1)-release (x86_64-pc-linux-gnu)
Copyright (C) 2020 Free Software Foundation, Inc.
Lizenz GPLv3+: GNU GPL Version 3 oder jünger <http://gnu.org/licenses/gpl.html>

Dies ist freie Software. Sie darf verändert und verteilt werden.
Es wird keine Garantie gewährt, soweit das Gesetz es zulässt.

This causes clicks shell completion activation to die with an exception because of the capitalized V in Version:

Traceback (most recent call last):
  File "/home/losinski/.local/bin/template-test", line 8, in <module>
    sys.exit(main())
  File "/home/losinski/.local/lib/python3.9/site-packages/click/core.py", line 1137, in __call__
    return self.main(*args, **kwargs)
  File "/home/losinski/.local/lib/python3.9/site-packages/click/core.py", line 1057, in main
    self._main_shell_completion(extra, prog_name, complete_var)
  File "/home/losinski/.local/lib/python3.9/site-packages/click/core.py", line 1132, in _main_shell_completion
    rv = shell_complete(self, ctx_args, prog_name, complete_var, instruction)
  File "/home/losinski/.local/lib/python3.9/site-packages/click/shell_completion.py", line 45, in shell_complete
    echo(comp.source())
  File "/home/losinski/.local/lib/python3.9/site-packages/click/shell_completion.py", line 324, in source
    self._check_version()
  File "/home/losinski/.local/lib/python3.9/site-packages/click/shell_completion.py", line 319, in _check_version
    raise RuntimeError(
RuntimeError: Couldn't detect Bash version, shell completion is not supported.

A quickfix would be to set LANG=C as environment on the bash --version call here: https://github.com/pallets/click/blob/main/src/click/shell_completion.py#L305. Another option would be

bash -c 'echo ${BASH_VERSION}'
5.1.4(1)-release

Environment:

• Python version: 3.9.2
• Click version: 8.0.1

[janLo]

The above PR is just to demonstrate the variable variant.