If subcommand is provided (and exists) and its first arg is -h/--help,
go ahead and intercept the call; redirecting to rbenv-help <subcommand>
This means subcommands and plugins need not handle --help flag
themselves
- Explicitly asking for help with `-h` or `--help` exits with 0 status
and displays help on stdout.
- Not providing any arguments to rbenv results in failure status and
displays version and help on stderr.
If `foo` didn't exist and `RBENV_VERSION=system rbenv which foo` was
called, the error message used to be misleading:
rbenv: version `system' is not installed
Instead, have the error message simply say that the command was not found.
Fixes#770
Useful in combination with `--bare` to list just the unique version
numbers without the extra directory entries that are symlinks to other
version numbers in the same directory.
This is for Linux desktop platforms that have Terminal application
configured to start shells in interactive but not login mode. Creating a
`~/.bash_profile` would also cause `~/.profile` to not run, which might
be a problem on Ubuntu which ships with a default `~/.profile`.
When `rbenv --version` is called, this now happens:
1. It changes into the directory where `libexec/rbenv--version` resides
and checks if it's a checkout of the rbenv repo (as opposed to
Homebrew checkout or something else). Then it reads the git revision.
2. If that failed, change to `$RBENV_ROOT` directory and repeat step 1.
This is required for the shims to handle `#!/usr/bin/env python3` in a
shebang, just like `python` is handled currently: it will set
`PYENV_DIR` to the root of the invoked script, which is required for a
`.python-version` script to get picked up from there.
This was rejected for rbenv, where it does not make much sense
(https://github.com/sstephenson/rbenv/pull/735).
Ref: https://github.com/yyuu/pyenv/pull/368#issuecomment-102806837
