[Gemfile] Require cocoapods-core from the feature-prepare_command branch

Gemfile

@@ -7,7 +7,7 @@ gemspec
 
 group :development do
   # To develop the deps in tandem use the `LOCAL GIT REPOS` feature of Bundler.
-  gem 'cocoapods-core',       :git => "https://github.com/CocoaPods/Core.git", :branch => 'master'
+  gem 'cocoapods-core',       :git => "https://github.com/CocoaPods/Core.git", :branch => 'feature-prepare_command'
   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

@@ -7,7 +7,7 @@ GIT
 
 GIT
   remote: https://github.com/CocoaPods/Core.git
-  revision: 2558ca127435e10a60349c503218e8a1e4eb494c
+  revision: 7738d01101994723deebb907f2414b78fcb6988e
   branch: feature-prepare_command
   specs:
     cocoapods-core (0.22.3)