rails 3 plugin install declare a specific branch

I want to install from a particul开发者_运维百科ar branch on a git repo, how do I do it?

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For plugins:

rails plugin install git://github.com/user/project.git -r branch_name

As gem, in your gemfile declare something like:

gem "project", :git => "git://github.com/user/project.git", :branch => "branch_name"