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`.
This avoids running `rbenv rehash` after installing libraries that don't
have executables, or after a no-op `bundle install` that didn't install
anything.
This is an attempt to work around the fact that Rubygems post_install
hooks may happen multiple times per single `bundle install` and ideally
we want `rbenv rehash` to run only once if new gems have been installed.
However, due to Bundler parallelism using `fork` on platforms that
support it, it's impossible for the child processes to communicate with
the master process to signal it to run `rbenv rehash` in the end.
This hooks into Bundler `install` command and runs `rbenv rehash` after
all gems have finished installing, but only if the install location was
system gems location and not a custom path (such as per-project
`vendor/bundle`).
This is limited because we can't tell whether any gems have been
installed at all, let alone do those gems have executables. However it's
better than having multiple `rbenv rehash` being run in parallel and
outputting confusing error messages as a result.
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.
If set by the user's environment, `git config --global` writes will go
to that destination instead of temporary $HOME. We definitely don't want
that.
Fixes#742
