def eval_gemfile(gemfile, contents = nil)
expanded_gemfile_path = Pathname.new(gemfile).expand_path(@gemfile && @gemfile.parent)
original_gemfile = @gemfile
@gemfile = expanded_gemfile_path
@gemfiles << expanded_gemfile_path
contents ||= Bundler.read_file(@gemfile.to_s)
instance_eval(contents.dup.untaint, gemfile.to_s, 1)
rescue Exception => e
message = "There was an error " \
"#{e.is_a?(GemfileEvalError) ? "evaluating" : "parsing"} " \
"`#{File.basename gemfile.to_s}`: #{e.message}"
raise DSLError.new(message, gemfile, e.backtrace, contents)
ensure
@gemfile = original_gemfile
end