Redmine

What does this warning mean, is it dangerous and how to deal with it:

Configuration:

D:\biz\apps\redmine_trunk>ruby script\rails server -e production
=> Booting WEBrick
=> Rails 3.2.8 application starting in production on http://0.0.0.0:3000
=> Call with -d to detach
=> Ctrl-C to shutdown server
d:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:251:in `block in require': ic
onv will be deprecated in the future, use String#encode instead.
[2012-10-14 14:52:26] INFO  WEBrick 1.3.1
[2012-10-14 14:52:26] INFO  ruby 1.9.3 (2012-04-20) [i386-mingw32]
[2012-10-14 14:52:26] INFO  WEBrick::HTTPServer#start: pid=3712 port=3000

Log:

Started GET "/" for 192.168.2.100 at 2012-10-14 14:53:37 +0300
Processing by WelcomeController#index as HTML
  Current user: admin (id=1)
  Rendered news/_news.html.erb (109.4ms)
  Rendered welcome/index.html.erb within layouts/base (281.2ms)
Completed 200 OK in 750ms (Views: 578.1ms | ActiveRecord: 140.6ms)
[2012-10-14 14:53:38] WARN  Could not determine content-length of response body. Set content-length of the response or s
et Response#chunked = true
[2012-10-14 14:53:38] WARN  Could not determine content-length of response body. Set content-length of the response or s
et Response#chunked = true
[2012-10-14 14:53:38] WARN  Could not determine content-length of response body. Set content-length of the response or s
et Response#chunked = true
[2012-10-14 14:53:38] WARN  Could not determine content-length of response body. Set content-length of the response or s
et Response#chunked = true