我试图通过rvm添加文档，没有遇到任何错误，然后当我去看看File.open时，收到了以下错误。有什么想法吗？
Mikes-MacBook-Pro:programs mwsage$ rvm docs generate
Installing rdoc-data...................
Mikes-MacBook-Pro:programs mwsage$ ri File.open
/Users/mwsage/.rvm/gems/ruby-1.9.3-p429@rails3tutorial2ndEd/gems/rdoc-4.0.1/lib/rdoc/store.rb:617:in `initialize': store at /Users/mwsage/.rvm/rubies/ruby-1.9.3-p429/share/ri/1.9.1/system missing file /Users/mwsage/.rvm/rubies/ruby-1.9.3-p429/share/ri/1.9.1/system/Kernel/open-c.ri for Kernel::open (RDoc::Store::MissingFileError)
from /Users/mwsage/.rvm/gems/ruby-1.9.3-p429@rails3tutorial2ndEd/gems/rdoc-4.0.1/lib/rdoc/store.rb:617:in `open'
from /Users/mwsage/.rvm/gems/ruby-1.9.3-p429@rails3tutorial2ndEd/gems/rdoc-4.0.1/lib/rdoc/store.rb:617:in `load_method'
from /Users/mwsage/.rvm/gems/ruby-1.9.3-p429@rails3tutorial2ndEd/gems/rdoc-4.0.1/lib/rdoc/ri/driver.rb:1185:in `load_method'
from /Users/mwsage/.rvm/gems/ruby-1.9.3-p429@rails3tutorial2ndEd/gems/rdoc-4.0.1/lib/rdoc/ri/driver.rb:1197:in `block in load_methods_matching'
from /Users/mwsage/.rvm/gems/ruby-1.9.3-p429@rails3tutorial2ndEd/gems/rdoc-4.0.1/lib/rdoc/ri/driver.rb:983:in `block in find_methods'
from /Users/mwsage/.rvm/gems/ruby-1.9.3-p429@rails3tutorial2ndEd/gems/rdoc-4.0.1/lib/rdoc/ri/driver.rb:982:in `each'
from /Users/mwsage/.rvm/gems/ruby-1.9.3-p429@rails3tutorial2ndEd/gems/rdoc-4.0.1/lib/rdoc/ri/driver.rb:982:in `find_methods'
from /Users/mwsage/.rvm/gems/ruby-1.9.3-p429@rails3tutorial2ndEd/gems/rdoc-4.0.1/lib/rdoc/ri/driver.rb:1194:in `load_methods_matching'
from /Users/mwsage/.rvm/gems/ruby-1.9.3-p429@rails3tutorial2ndEd/gems/rdoc-4.0.1/lib/rdoc/ri/driver.rb:1213:in `lookup_method'
from /Users/mwsage/.rvm/gems/ruby-1.9.3-p429@rails3tutorial2ndEd/gems/rdoc-4.0.1/lib/rdoc/ri/driver.rb:508:in `add_method'
from /Users/mwsage/.rvm/gems/ruby-1.9.3-p429@rails3tutorial2ndEd/gems/rdoc-4.0.1/lib/rdoc/ri/driver.rb:783:in `display_method'
from /Users/mwsage/.rvm/gems/ruby-1.9.3-p429@rails3tutorial2ndEd/gems/rdoc-4.0.1/lib/rdoc/ri/driver.rb:802:in `display_name'
from /Users/mwsage/.rvm/gems/ruby-1.9.3-p429@rails3tutorial2ndEd/gems/rdoc-4.0.1/lib/rdoc/ri/driver.rb:827:in `block in display_names'
from /Users/mwsage/.rvm/gems/ruby-1.9.3-p429@rails3tutorial2ndEd/gems/rdoc-4.0.1/lib/rdoc/ri/driver.rb:824:in `each'
from /Users/mwsage/.rvm/gems/ruby-1.9.3-p429@rails3tutorial2ndEd/gems/rdoc-4.0.1/lib/rdoc/ri/driver.rb:824:in `display_names'
from /Users/mwsage/.rvm/gems/ruby-1.9.3-p429@rails3tutorial2ndEd/gems/rdoc-4.0.1/lib/rdoc/ri/driver.rb:1361:in `run'
from /Users/mwsage/.rvm/gems/ruby-1.9.3-p429@rails3tutorial2ndEd/gems/rdoc-4.0.1/lib/rdoc/ri/driver.rb:356:in `run'
from /Users/mwsage/.rvm/gems/ruby-1.9.3-p429@rails3tutorial2ndEd/gems/rdoc-4.0.1/bin/ri:12:in `<top (required)>'
from /Users/mwsage/.rvm/gems/ruby-1.9.3-p429@rails3tutorial2ndEd/bin/ri:23:in `load'
from /Users/mwsage/.rvm/gems/ruby-1.9.3-p429@rails3tutorial2ndEd/bin/ri:23:in `<main>'