Running this should only require Rails 2.2.2 or later, and the command line
interfaces for sqlite3 and curl.  Tested on Ubuntu Linux 9.04 ("Jaunty
Jackalope") and Mac OSX 10.5.6 ("Leopard").

Installation of all necessary dependencies from a fresh install of Ubuntu 9.04:

  sudo apt-get install rails git-core sqlite3 curl
  sudo gem install rubygems-update
  sudo /var/lib/gems/1.8/bin/update_rubygems
  sudo gem install rails
  sudo gem sources -a http://gems.github.com
  sudo gem install rubys-gorp

Execution instructions:

  This is a library which, among other things, will interpret ARGV.  Here's
  an example based on http://github.com/rubys/awdwr:

  ruby makedepot.rb [VERSION] [--bundle] [--restore] [RANGE]... [--save]

    "VERSION" - specifies the Rails version to test.  Examples:
      edge
      _2.2.2_
      ~/git

    "--bundle" - bundle this version of rails with each Rails app generated.
      - if libraries are listed in the RUBYLIB environment variable, they
        will be added as directories to the Gemfile before making the bundle
        (adding '--system' will only bundle system gems)

    "--restore" - restore from snapshot before resuming execution

    "RANGE"   - specifies a set of sections to execute.  Examples:
      6.2..6.5
      7.1-9.5
      16

    "--save"  - save snapshot after execution completes

    "--rails-debug" - turn on BACKTRACE and Thread.abort_on_exception

Tests against the output produced (e.g., makedepot.html) can also be run
separately:

  ruby checkdepot.rb [partial]

  "partial" means that tests which cover sections that are not included in
    makedepot.html are to be omitted.