Requested in https://github.com/pyenv/pyenv/issues/2680
for deployments with a stock `.pyenv-version` that can use any
of a number of Python versions
and for compatibility with `uv`.
* Support `pyenv local --force`
* Support `pyenv-version-file-write --force`
* Support `pyenv version-name --force`
* Ignore missing versions when searching for executables
* Display "commmand not found" even when there are nonexistent versions
* exec.bats: replace `python` and `rspec` with something that doesn't exist globally, either
in Ubuntu Github CI, `python` exists globally
Fixes use of version specifiers like `python-3.12`, which:
- have an explicit `python-` prefix
- are using a major version alias that has to be resolved
to an exact version.
Also simplified the conditional for the already
working case, since it had two branches that were virtually identical.
All scripts in libexec/ (excluding pyenv) are called through pyenv,
therefore the shebang lines are not necessary. On some systems this
provides a measurable increase in performance of the shell prompt.
Related to pyenv/pyenv-virtualenv#259
