Custom gem method for local using gems locally (courtesy of ruby-amqp)

custom_gem.rb

# Use local clones if possible.
# If you want to use your local copy, just symlink it to vendor.
def custom_gem(name, options = Hash.new)
  local_path = File.expand_path("../vendor/#{name}", __FILE__)
  if File.exist?(local_path)
    gem name, options.merge(:path => local_path).delete_if { |key, _| [:git, :branch].include?(key) }
  else
    gem name, options
  end
end