class Bundler::RubygemsIntegration

def replace_gem(specs, specs_by_name)
  reverse_rubygems_kernel_mixin
  executables = nil
  kernel = (class << ::Kernel; self; end)
  [kernel, ::Kernel].each do |kernel_class|
    redefine_method(kernel_class, :gem) do |dep, *reqs|
      if executables && executables.include?(File.basename(caller.first.split(":").first))
        break
      end
      reqs.pop if reqs.last.is_a?(Hash)
      unless dep.respond_to?(:name) && dep.respond_to?(:requirement)
        dep = Gem::Dependency.new(dep, reqs)
      end
      if spec = specs_by_name[dep.name]
        return true if dep.matches_spec?(spec)
      end
      message = if spec.nil?
        target_file = begin
                        Bundler.default_gemfile.basename
                      rescue GemfileNotFound
                        "inline Gemfile"
                      end
        "#{dep.name} is not part of the bundle." \
        " Add it to your #{target_file}."
      else
        "can't activate #{dep}, already activated #{spec.full_name}. " \
        "Make sure all dependencies are added to Gemfile."
      end
      e = Gem::LoadError.new(message)
      e.name = dep.name
      e.requirement = dep.requirement
      raise e
    end
    # backwards compatibility shim, see https://github.com/rubygems/bundler/issues/5102
    kernel_class.send(:public, :gem) if Bundler.feature_flag.setup_makes_kernel_gem_public?
  end
end