source_requirements

# File lib/bundler/definition.rb, line 909
    def source_requirements
      # Load all specs from remote sources
      index

      # Record the specs available in each gem's source, so that those
      # specs will be available later when the resolver knows where to
      # look for that gemspec (or its dependencies)
      default = sources.default_source
      source_requirements = { :default => default }
      default = nil unless Bundler.feature_flag.lockfile_uses_separate_rubygems_sources?
      dependencies.each do |dep|
        next unless source = dep.source || default
        source_requirements[dep.name] = source
      end
      metadata_dependencies.each do |dep|
        source_requirements[dep.name] = sources.metadata_source
      end
      source_requirements["bundler"] = sources.metadata_source # needs to come last to override
      source_requirements
    end