Why is rails installing a newer version when I run bundle? - ruby-on-rails

Question

I am trying to start a new rails project and I would like to stick with rails 3.1.3. However, when I run the command rails new projectname I get the following output:
create
create README.rdoc
create Rakefile
create config.ru
create .gitignore
create Gemfile
create app
...
create config
...
create config/database.yml
create db
...
create public/robots.txt
create script
create script/rails
create test/fixtures
create test/fixtures/.gitkeep
...
create tmp/cache
create tmp/cache/assets
create vendor/assets/javascripts
...
create vendor/plugins/.gitkeep
run bundle install
Fetching source index for https://rubygems.org/
Using rake (0.9.2.2)
Using i18n (0.6.0)
Using multi_json (1.0.4)
Using activesupport (3.2.0.rc2)
Using builder (3.0.0)
Using activemodel (3.2.0.rc2)
Using erubis (2.7.0)
Using journey (1.0.0)
Using rack (1.4.0)
Using rack-cache (1.1)
Using rack-test (0.6.1)
Using hike (1.2.1)
Using tilt (1.3.3)
Using sprockets (2.1.2)
Using actionpack (3.2.0.rc2)
Using mime-types (1.17.2)
Using polyglot (0.3.3)
Using treetop (1.4.10)
Using mail (2.3.0)
Using actionmailer (3.2.0.rc2)
Using arel (3.0.0)
Using tzinfo (0.3.31)
Using activerecord (3.2.0.rc2)
Using activeresource (3.2.0.rc2)
Using bundler (1.0.21)
Using coffee-script-source (1.2.0)
Using execjs (1.2.13)
Using coffee-script (2.2.0)
Using rack-ssl (1.3.2)
Using json (1.6.5)
Using rdoc (3.12)
Using thor (0.14.6)
Using railties (3.2.0.rc2)
Using coffee-rails (3.2.1)
Using jquery-rails (2.0.0)
Installing rails (3.2.0.rc2) # WTF?
Using sass (3.1.12)
Using sass-rails (3.2.3)
Using sqlite3 (1.3.5)
Using uglifier (1.2.2)
Your bundle is complete! Use `bundle show [gemname]` to see where a bundled gem is installed.
I'd like everything to remain version 3.1. Why does the rails command automatically update itself to 3.2.0.rc2? How can I make sure that everything I do is using 3.1.3 versions of everything?
Thanks.

Answer 1

It is relatively little known fact that you can specify the rails version for a new application _like.this_
rails _3.1.3_ projectname
will work assuming 3.1.3 is installed (gem install rails -v3.1.3 otherwise)
This also works with rails 2 apps, i.e. pre-bundler and will create a rails2 looking application in these cases, e.g. rails _2.3.8_ projectname Again gem install rails -v2.3.8 if necessary (i.e. first time usage on that machine).
Longer term make sure you are using rvm (now a defacto standard) and you can use that toset your default rails (as well as ruby).
Removing the old version can be done with sudo gem uninstall rails -v 3.2.0.rc2