Chruby 2.4.0 returning a pre-release #387

First: thanks for chruby, love it.

I ran into a problem over christmas regarding using the release version of 2.4.0 and chruby. I've got all the pre-release versions of 2.4.0 on my machine

$ chruby
# ...
   ruby-2.4.0
   ruby-2.4.0-preview1
   ruby-2.4.0-preview2
   ruby-2.4.0-preview3
 * ruby-2.4.0-rc1
   ruby-trunk
   schneems-dev

I'm using what I think is the latest chruby

$ chruby --version
chruby: 0.3.9

When I run

$ chruby 2.4.0

I get

$ ruby -v
ruby 2.4.0rc1 (2016-12-12 trunk 57064) [x86_64-darwin16]

If I want the release version I have to be really explicit

$ chruby ruby-2.4.0
$ ruby -v
ruby 2.4.0p0 (2016-12-24 revision 57164) [x86_64-darwin16]

Is chruby 2.4.0 supposed to give me the released version, or is the correct fix to uninstall all the pre-releases?