This is the remaining part of
c69d9a1128.
commit c69d9a1128
Author: Mislav Marohnić <mislav.marohnic@gmail.com>
Date: Mon Oct 13 12:39:47 2014 +0200
Isolate rbenv-which tests from any `.ruby-version` file on the system
Having a `.ruby-version` file in any of the parent directories of the
local clone of rbenv could cause the test suite to fail because it
wasn't expecting a local version to be set.