Need to backport the tap method from chef into ohai as it's causing plugin failures

See stack trace

[Thu, 28 Apr 2011 15:44:18 -0700] DEBUG: has_ec2_mac? == true
[Thu, 28 Apr 2011 15:44:18 -0700] DEBUG: can_metadata_connect? == true
[Thu, 28 Apr 2011 15:44:18 -0700] DEBUG: looks_like_ec2? == true
[Thu, 28 Apr 2011 15:44:18 -0700] DEBUG: Plugin ec2 threw exception #<NoMethodError: undefined method `tap' for #<Net::HTTP 169.254.169.254:80 open=true>> /usr/lib/ruby/gems/1.8/gems/ohai-0.6.4/lib/ohai/mixin/ec2_metadata.rb:59:in `http_client'
/usr/lib/ruby/gems/1.8/gems/ohai-0.6.4/lib/ohai/mixin/ec2_metadata.rb:64:in `fetch_metadata'
/usr/lib/ruby/gems/1.8/gems/ohai-0.6.4/lib/ohai/plugins/ec2.rb:51:in `from_file'
/usr/lib/ruby/gems/1.8/gems/ohai-0.6.4/lib/ohai/system.rb:190:in `require_plugin'
/usr/lib/ruby/gems/1.8/gems/ohai-0.6.4/lib/ohai/system.rb:185:in `each'
/usr/lib/ruby/gems/1.8/gems/ohai-0.6.4/lib/ohai/system.rb:185:in `require_plugin'
/usr/lib/ruby/gems/1.8/gems/ohai-0.6.4/lib/ohai/system.rb:117:in `all_plugins'
/usr/lib/ruby/gems/1.8/gems/ohai-0.6.4/lib/ohai/system.rb:110:in `each'
/usr/lib/ruby/gems/1.8/gems/ohai-0.6.4/lib/ohai/system.rb:110:in `all_plugins'
/usr/lib/ruby/gems/1.8/gems/ohai-0.6.4/lib/ohai/system.rb:108:in `each'
/usr/lib/ruby/gems/1.8/gems/ohai-0.6.4/lib/ohai/system.rb:108:in `all_plugins'
/usr/lib/ruby/gems/1.8/gems/ohai-0.6.4/lib/ohai/application.rb:97:in `run_application'
/usr/lib/ruby/gems/1.8/gems/ohai-0.6.4/lib/ohai/application.rb:75:in `run'
/usr/lib/ruby/gems/1.8/gems/ohai-0.6.4/bin/ohai:51
/usr/bin/ohai:19:in `load'
/usr/bin/ohai:19
[Thu, 28 Apr 2011 15:44:18 -0700] DEBUG: Loading plugin uptime