What does “WARN Could not determine content-length of response body.” mean and how to I get rid of it?

Question

Since upgrading to Rails 3.1 I\'m seeing this warning message in my development log:

WARN Could not determine content-length of response body. Set co

Answer 1

Another workaround that removes the offending line from webrick. It's just not that useful:

cd `which ruby`/../../lib/ruby/1.9.1/webrick/ && sed -i '.bak' -e'/logger.warn/d' httpresponse.rb

(you may need to sudo)