Rails bundler not installing spree gems

Question

I'm trying to create a new rails application that uses spree. I am trying to install the spree_fancy gem and was told to append it to my gemfile.

Here is my gem file:

source 'https://rubygems.org'


gem 'rails', '4.1.4'
gem 'sqlite3'
gem 'sass-rails', '~> 4.0.3'
gem 'uglifier', '>= 1.3.0'
gem 'coffee-rails', '~> 4.0.0'

gem 'jquery-rails'
gem 'turbolinks'
gem 'jbuilder', '~> 2.0'
gem 'sdoc', '~> 0.4.0',          group: :doc

gem 'spring',        group: :development


gem 'spree', '2.3.1'
gem 'spree_gateway', :git => 'https://github.com/spree/spree_gateway.git', :branch => '2-3-stable'
gem 'spree_auth_devise', :git => 'https://github.com/spree/spree_auth_devise.git', :branch => '2-3-stable'

gem 'spree_fancy', :git => 'git://github.com/spree/spree_fancy.git', :branch => '2-1-stable'

However, after running bundle install , I receive the following error:

Bundler could not find compatible versions for gem "spree_core":
  In Gemfile:
    spree_fancy (>= 0) ruby depends on
      spree_core (~> 2.1.0) ruby

    spree (= 2.3.1) ruby depends on
      spree_core (2.3.1)

How can i fix this?

UPDATE :

As suggested, I changed the spree_fancy branch from 2.1 to 2.3, and I now have a new error

Bundler could not find compatible versions for gem "i18n":
  In snapshot (Gemfile.lock):
    i18n (0.6.11)

  In Gemfile:
    spree (= 2.3.1) ruby depends on
      spree_core (= 2.3.1) ruby depends on
        i18n (= 0.6.9) ruby

Answer 1

You are using incompatible version of Spree and Spree Fancy.

Try changing:

gem 'spree_fancy', :git => 'git://github.com/spree/spree_fancy.git', :branch => '2-1-stable'

to

gem 'spree_fancy', :git => 'git://github.com/spree/spree_fancy.git', :branch => '2-3-stable'

and run bundle install again.