Merge pull request #480 from olleolleolle/try-with-5-2-stable

Gemfile for 5.2: use 5-2-stable branch

Author: kaspth

gemfiles/rails_5_2.gemfile

@@ -2,9 +2,11 @@
 
 source "https://rubygems.org"
 
+git_source(:github) { |repo_name| "https://github.com/#{repo_name}.git" }
+
 gem "rake"
 gem "mocha", require: false
 gem "appraisal"
-gem "rails", "~> 5.2.0"
+gem "rails", "~> 5.2", github: 'rails/rails', branch: '5-2-stable'
 
 gemspec path: "../"