Can't bundle 2-0-stable when using spree/spree/2-0-stable

[BDQ]

Version conflicts between 2.0.0 and 2.0.0.rc1

[danidrops]

Is this why when I add
gem 'spree_paypal_express', :git => 'git://github.com/spree/spree_paypal_express.git', branch: => '2-0-stable'
to my Gemfile and bundle install, it completely ignores this gem? No errors no complaints, just ignored! I'm using spree 2.0.1 Is this related to the current build failing status of this gem?