[Bundle] Update.

Gemfile

@@ -8,7 +8,7 @@ gemspec
 group :development do
   # To develop the deps in tandem use the `LOCAL GIT REPOS` feature of Bundler.
   # For more info see http://bundler.io/git.html#local
-  gem 'cocoapods-core',       :git => "https://github.com/CocoaPods/Core.git", :branch => 'master'
+  gem 'cocoapods-core',       :git => "https://github.com/CocoaPods/Core.git", :branch => 'lookback-pods-by-config'
   gem 'xcodeproj',            :git => "https://github.com/CocoaPods/Xcodeproj.git", :branch => 'master'
   gem 'cocoapods-downloader', :git => "https://github.com/CocoaPods/cocoapods-downloader.git", :branch => 'master'
   gem 'claide',               :git => 'https://github.com/CocoaPods/CLAide.git', :branch => 'master'

Gemfile.lock

@@ -7,8 +7,8 @@ GIT
 
 GIT
   remote: https://github.com/CocoaPods/Core.git
-  revision: d281be39c464418c0b0ee8ba4788c4d2ce074de6
-  branch: master
+  revision: 73c5a6b0c6331c4bfdc0d58360abf0f3f13beb56
+  branch: lookback-pods-by-config
   specs:
     cocoapods-core (0.29.0)
       activesupport (>= 3.2.15, < 4)