gistfile1.txt

gem "machinist", '>=2.0.0.beta1'
gem "machinist_mongo"

# =>

Using machinist (1.0.6) 
Using machinist_mongo (1.1.1) 

=====================================

gem "machinist", '>=2.0.0.beta1'
gem "machinist_mongo", '>=2.0.0.pre'

# =>  

Bundler could not find compatible versions for gem "machinist":
  In Gemfile:
    machinist_mongo (>= 2.0.0.pre) depends on
      machinist (~> 1.0.6)

    machinist (2.0.0.beta2)

=====================================

gem "machinist", '>=2.0.0.beta2'     # beta1 changed to beta2
gem "machinist_mongo", '>=2.0.0.pre'

# => 

Could not find gem 'machinist (>= 2.0.0.beta2, runtime)' in any of the gem sources.

 % gem list -r --pre machinist

*** REMOTE GEMS ***

machinist (2.0.0.beta2 ruby, 2.0.0.beta1 ruby)

=====================================

gem "machinist", '>=2.0.0.beta2'
gem "machinist_mongo", :git => 'http://github.com/nmerouze/machinist_mongo.git', :branch => 'machinist2'
# this branch is supposed to be for machinist2

# => 

Using machinist (1.0.6) 
Using machinist_mongo (1.1.1)