The rehash process will now discover executables in additional locations:
- `~/.gem/ruby/<version>/bin/*`
- `$GEM_HOME/bin`
The `rbenv which` (and thus `rbenv exec`) command will also search these locations when looking up a command. This enables shims to dispatch calls to executables added by `gem install --user-install`.
Note that this support is limited:
- It will only work with C Ruby, as it's difficult to guess the `~/.gem/<engine>/<version>` directory for other Rubies without actually loading Ruby;
- It will only work for RBENV_VERSION values in the format `X.Y.Z` and not "system".
It doesn't need to be a bash array and we don't need a separate index of
shims registered. Simply keep everything in a space-separated string and
use that as an index as well.
This assumes that executable names *never* have spaces in them.
It doesn't exist as a builtin, and it doesn't seem there is a way to
detect support for a shell builtin that is portable. So, just detect
fish and don't the rehash command at all.
Fixes#478
`$SHELL` variable is a terrible way of detecting the current shell
because it's not even supposed to reflect the current shell; it's meant
for keeping the value of the default shell for programs to start.
If an explicit `<shell>` argument wasn't passed to `rbenv init`, it
tries to detect the shell by getting the name of its parent process. If
this fails, it falls back on the value of `$SHELL` as before.
Furthermore, `rbenv init` will set the RBENV_SHELL variable in the
current shell to the value of the detected shell so that `sh-shell` and
`sh-rehash` commands don't have to repeat the detection.
