Description of problem:
Since rack-1.1.0 stores headers in an array and not a string, rubygem-actionpack requires the following patch:

http://cvs.fedoraproject.org/viewvc/rpms/rubygem-actionpack/F-13/rubygem-actionpack-2.3.5-rack-compat.patch?view=markup

Attached is an updated patch with one addition, removing a newline from being prepended when multiple headers are present. 

This newline made sense in the context of the headers string as it acted as a delimiter. 

But in the context of the headers array it does not, and infact it causes breakage in actionpack/action_controller/integration.rb line 334 which will throw the following exception if the first character in the header string is a newline (as it is if there are multiple headers)

You have a nil object when you didn't expect it!
You might have expected an instance of ActiveRecord::Base.
The error occurred while evaluating nil.[] (NoMethodError)

The patch with the removal of the newline can be found here

http://mo.morsi.org/files/patches/rubygem-actionpack-2.3.5-rack-compat.patch

Version-Release number of selected component (if applicable):
rubygem-actionpatch-2.3.5

How reproducible:
Occurs when running the deltacloud feature suite against rubygems installed via yum.

Steps to Reproduce:
1. Check out deltacloud as described here http://deltacloud.org/contribute.html
2. cd aggregator/src
3. rake feature
  
Actual results:
Exceptions thrown concerning nil class

Expected results:
Feature suite successfully executes (as it does when my patch is applied against actionpack 2.3.5)