From 4c55082e7c0bcf0c6bb2b1401286fda466ad3248 Mon Sep 17 00:00:00 2001
From: Jack Nagel <jacknagel@gmail.com>
Date: Tue, 10 Sep 2013 15:08:03 -0500
Subject: [PATCH] update: restore previous state when interrupted

Fixes Homebrew/homebrew#19460.
Closes Homebrew/homebrew#22375.
---
 Library/Homebrew/cmd/update.rb | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/Library/Homebrew/cmd/update.rb b/Library/Homebrew/cmd/update.rb
index b3248c5cb3..09e68f6884 100644
--- a/Library/Homebrew/cmd/update.rb
+++ b/Library/Homebrew/cmd/update.rb
@@ -86,11 +86,19 @@ class Updater
     # the refspec ensures that 'origin/master' gets updated
     args << "refs/heads/master:refs/remotes/origin/master"
 
-    safe_system "git", *args
+    reset_on_interrupt { safe_system "git", *args }
 
     @current_revision = read_current_revision
   end
 
+  def reset_on_interrupt
+    ignore_interrupts { yield }
+  ensure
+    if $?.signaled? && $?.termsig == 2 # SIGINT
+      safe_system "git", "reset", "--hard", @initial_revision
+    end
+  end
+
   # Matches raw git diff format (see `man git-diff-tree`)
   DIFFTREE_RX = /^:[0-7]{6} [0-7]{6} [0-9a-fA-F]{40} [0-9a-fA-F]{40} ([ACDMR])\d{0,3}\t(.+?)(?:\t(.+))?$/