From ef4347b898520053ff7b4b1a3f0eaae80b7a4f9f Mon Sep 17 00:00:00 2001
From: Jack Nagel <jacknagel@gmail.com>
Date: Thu, 18 Dec 2014 12:57:37 -0500
Subject: [PATCH] Start versioning cached git clones

---
 Library/Homebrew/download_strategy.rb | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/Library/Homebrew/download_strategy.rb b/Library/Homebrew/download_strategy.rb
index 65d47c1612..9e3f29d441 100644
--- a/Library/Homebrew/download_strategy.rb
+++ b/Library/Homebrew/download_strategy.rb
@@ -534,6 +534,10 @@ class GitDownloadStrategy < VCSDownloadStrategy
     "git"
   end
 
+  def cache_version
+    0
+  end
+
   def update
     cached_location.cd do
       config_repo
@@ -600,7 +604,10 @@ class GitDownloadStrategy < VCSDownloadStrategy
 
   def clone_repo
     safe_system 'git', *clone_args
-    cached_location.cd { update_submodules } if submodules?
+    cached_location.cd do
+      safe_system "git", "config", "homebrew.cacheversion", cache_version
+      update_submodules if submodules?
+    end
   end
 
   def checkout