Resolving dependencies...
Bundler could not find compatible versions for gem "railties":
  In Gemfile:
    requirejs-rails (>= 0) ruby depends on
      railties (~> 3.1.1) ruby

    rails (= 4.0.0.rc2) ruby depends on
      railties (4.0.0.rc2)

Bundler could not find compatible versions for gem "rails":
  In Gemfile:
    requirejs-rails (>= 0) ruby depends on
      rails (~> 3.1.1) ruby

    rails (4.0.0.rc2)

但如果我只使用bundle,我会得到以下内容：

Resolving dependencies...
Bundler could not find compatible versions for gem "activesupport":
  In snapshot (Gemfile.lock):
    activesupport (3.2.2)

  In Gemfile:
    rails (= 4.0.0.rc2) ruby depends on
      activesupport (= 4.0.0.rc2) ruby

Running `bundle update` will rebuild your snapshot from scratch,using only
the gems in your Gemfile,which may resolve the conflict.

据说,针对Rails 4 Beta here更新了requirejs-rail.仍然不确定导致该问题的依赖性,以及迫使gem出现的版本.

的Gemfile：

source 'https://rubygems.org'
gem 'rails','4.0.0.rc2'

group :development,:test do
  gem 'railroady'
  gem 'sqlite3'
  # For linux support
  gem 'therubyracer'
end

group :production do
  gem 'pg'
  gem 'thin'
end

gem 'sass-rails','~> 4.0.0.rc1'
gem 'coffee-rails','~> 4.0.0'
gem 'uglifier','>= 1.0.3'

gem 'colorize'
gem 'jquery-ui-rails'
gem 'jquery-rails'
gem 'rails-backbone'
gem 'bootstrap-sass','~> 2.3.0.0'
gem 'requirejs-rails'
gem 'ejs'
gem 'devise'
gem 'better_errors','>= 0.2.0',:group => :development
gem 'binding_of_caller','>= 0.6.8',:group => :development
gem 'd3_rails'

# for a better way of looking at the rake routes by calling rake color_routes in the console
gem 'color_routes'
# lets us know which user is logged in,and store in a gloabel variable gon{}
gem 'gon'
#browser detection
gem 'browser'

# FOR EASY TRANISTION TO Rails 4
gem 'protected_attributes'
gem 'rails-observers'
gem 'actionpack-page_caching'
gem 'actionpack-action_caching'

Gemfile.lock的：

GEM
  remote: https://rubygems.org/
  specs:
    actionmailer (3.2.2)
      actionpack (= 3.2.2)
      mail (~> 2.4.0)
    actionpack (3.2.2)
      activemodel (= 3.2.2)
      activesupport (= 3.2.2)
      builder (~> 3.0.0)
      erubis (~> 2.7.0)
      journey (~> 1.0.1)
      rack (~> 1.4.0)
      rack-cache (~> 1.1)
      rack-test (~> 0.6.1)
      sprockets (~> 2.1.2)
    activemodel (3.2.2)
      activesupport (= 3.2.2)
      builder (~> 3.0.0)
    activerecord (3.2.2)
      activemodel (= 3.2.2)
      activesupport (= 3.2.2)
      arel (~> 3.0.2)
      tzinfo (~> 0.3.29)
    activeresource (3.2.2)
      activemodel (= 3.2.2)
      activesupport (= 3.2.2)
    activesupport (3.2.2)
      i18n (~> 0.6)
      multi_json (~> 1.0)
    arel (3.0.2)
    bcrypt-ruby (3.0.1)
    binding_of_caller (0.7.1)
      debug_inspector (>= 0.0.1)
    bootstrap-sass (2.3.0.1)
      sass (~> 3.2)
    browser (0.1.6)
    builder (3.0.4)
    coffee-rails (3.2.2)
      coffee-script (>= 2.2.0)
      railties (~> 3.2.0)
    coffee-script (2.2.0)
      coffee-script-source
      execjs
    coffee-script-source (1.6.2)
    color_routes (1.0.0)
    colorize (0.5.8)
    d3_rails (3.1.6)
      railties (>= 3.1.0)
    daemons (1.1.9)
    debug_inspector (0.0.2)
    devise (2.2.4)
      bcrypt-ruby (~> 3.0)
      orm_adapter (~> 0.1)
      railties (~> 3.1)
      warden (~> 1.2.1)
    ejs (1.1.1)
    erubis (2.7.0)
    eventmachine (1.0.3)
    execjs (1.4.0)
      multi_json (~> 1.0)
    gon (4.1.0)
      actionpack (>= 2.3.0)
      json
    hike (1.2.2)
    i18n (0.6.4)
    journey (1.0.4)
    jquery-rails (2.1.4)
      railties (>= 3.0,< 5.0)
      thor (>= 0.14,< 2.0)
    jquery-ui-rails (4.0.3)
      jquery-rails
      railties (>= 3.1.0)
    json (1.8.0)
    libv8 (3.11.8.17)
    mail (2.4.4)
      i18n (>= 0.4.0)
      mime-types (~> 1.16)
      treetop (~> 1.4.8)
    mime-types (1.23)
    multi_json (1.7.3)
    orm_adapter (0.4.0)
    pg (0.15.1)
    polyglot (0.3.3)
    rack (1.4.5)
    rack-cache (1.2)
      rack (>= 0.4)
    rack-ssl (1.3.3)
      rack
    rack-test (0.6.2)
      rack (>= 1.0)
    railroady (1.1.0)
    rails (3.2.2)
      actionmailer (= 3.2.2)
      actionpack (= 3.2.2)
      activerecord (= 3.2.2)
      activeresource (= 3.2.2)
      activesupport (= 3.2.2)
      bundler (~> 1.0)
      railties (= 3.2.2)
    rails-backbone (0.9.10)
      coffee-script (~> 2.2.0)
      ejs (~> 1.1.1)
      jquery-rails (~> 2.1.3)
      railties (>= 3.1.0)
    railties (3.2.2)
      actionpack (= 3.2.2)
      activesupport (= 3.2.2)
      rack-ssl (~> 1.3.2)
      rake (>= 0.8.7)
      rdoc (~> 3.4)
      thor (~> 0.14.6)
    rake (10.0.4)
    rdoc (3.12.2)
      json (~> 1.4)
    ref (1.0.5)
    requirejs-rails (0.9.1)
      railties (>= 3.1.1,< 3.3)
    sass (3.2.9)
    sass-rails (3.2.6)
      railties (~> 3.2.0)
      sass (>= 3.1.10)
      tilt (~> 1.3)
    sprockets (2.1.3)
      hike (~> 1.2)
      rack (~> 1.0)
      tilt (~> 1.1,!= 1.3.0)
    sqlite3 (1.3.7)
    therubyracer (0.11.4)
      libv8 (~> 3.11.8.12)
      ref
    thin (1.5.1)
      daemons (>= 1.0.9)
      eventmachine (>= 0.12.6)
      rack (>= 1.0.0)
    thor (0.14.6)
    tilt (1.4.1)
    treetop (1.4.12)
      polyglot
      polyglot (>= 0.3.1)
    tzinfo (0.3.37)
    uglifier (2.1.1)
      execjs (>= 0.3.0)
      multi_json (~> 1.0,>= 1.0.2)
    warden (1.2.1)
      rack (>= 1.0)

PLATFORMS
  ruby

DEPENDENCIES
  binding_of_caller (>= 0.6.8)
  bootstrap-sass (~> 2.3.0.0)
  browser
  coffee-rails (~> 3.2.1)
  color_routes
  colorize
  d3_rails
  devise
  ejs
  gon
  jquery-rails
  jquery-ui-rails
  pg
  railroady
  rails (= 3.2.2)
  rails-backbone
  requirejs-rails
  sass-rails (~> 3.2.3)
  sqlite3
  therubyracer
  thin
  uglifier (>= 1.0.3)