It doesn't try to chdir into RBENV_ROOT anymore because that might be
a location of an unrelated rbenv install that might have a different
version than the current one that is installed e.g. via a package
manager such as Homebrew.
Now just tries the repo where the source files (`libexec/*`) are
located, and if that isn't a valid rbenv repo, bail out early.
Expose a `version-origin` hook.
It is invoked *before* the traditional `rbenv-version-file` lookup. Because `version-origin` is traditionally run immediately after `version-name`, then any plugin hooks that alter `version-name` would have done so. Thus, running `version-origin` prior to printing the origin gives those plugins a chance to alter the `version-origin` to match.
If any of the hooks set `$RBENV_VERSION_ORIGIN`, then it is used as the return value. Otherwise, the existing logic continues to return "environment variable" or "filename" as appropriate.
This change, in conjunction with the `version-name` hook, makes a clean seam by which plugins can inject their own ruby version setting logic. Using this seam, as opposed to altering `$RBENV_COMMAND_PATH` from the `which` hook, means that the version name and origin are set more reliably and so `version`, `version-name`, `version-origin` and `which` all work as expected. Indeed, even PS1 works now.
Expose a `version-name` hook.
It is invoked *after* the traditional `RBENV_VERSION` lookup. Which means hook scripts can interrogate `$RBENV_VERSION_FILE` and/or `$RBENV_VERSION` (or use the executables).
The hooks are then run, giving plugins a chance to alter `RBENV_VERSION`. Once the hooks have run, we now have (in `$RBENV_VERSION`) the actual version we want to use (or it's empty which defaults to `system` per normal). Lastly, the same logic remains for checking if the version exists, or trimming the `ruby-` prefix.
Prime example: the ruby-bundler-ruby-version plugin can select a ruby by using the `ruby` directive from the `Gemfile` if a local `.ruby-version` doesn't exist.
Can be used for `.ruby-version` file lookup in the ancestry of a
specific directory. In this mode of operation, global version files
aren't taken into consideration, and the command fails unless a local
version file was found.
