Ruby on rails 没有要加载的文件--activesupport（LoadError）

我无法让db2s3gem在我的rails3应用程序上运行

  /usr/lib/ruby/gems/1.8/gems/db2s3-0.3.1/lib/db2s3.rb:1:in `require': no such file  to  load -- activesupport (LoadError)
from /usr/lib/ruby/gems/1.8/gems/db2s3-0.3.1/lib/db2s3.rb:1
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0/lib/bundler/runtime.rb:64:in `require'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0/lib/bundler/runtime.rb:64:in `require'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0/lib/bundler/runtime.rb:62:in `each'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0/lib/bundler/runtime.rb:62:in `require'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0/lib/bundler/runtime.rb:51:in `each'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0/lib/bundler/runtime.rb:51:in `require'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0/lib/bundler.rb:112:in `require'
from /home/sean/chief/config/application.rb:7
from /usr/lib/ruby/gems/1.8/gems/railties-3.0.0/lib/rails/commands.rb:28:in        `require'
from /usr/lib/ruby/gems/1.8/gems/railties-3.0.0/lib/rails/commands.rb:28
from /usr/lib/ruby/gems/1.8/gems/railties-3.0.0/lib/rails/commands.rb:27:in `tap'
from /usr/lib/ruby/gems/1.8/gems/railties-3.0.0/lib/rails/commands.rb:27
from script/rails:6:in `require'
from script/rails:6

---

我发现它被固定在一些叉子上：

但看看另一个叉子也

---

另外，我不知道替代方案，但我见过备份gem，它曾经做过同样的事情，甚至更多。

看起来该项目自2009年底以来就没有被涉及过，我猜它与rails 3不兼容。那么有其他的建议吗？