test-bot: exclude Taps dir from root cleanup

Library/Homebrew/cmd/test-bot.rb

@@ -645,7 +645,7 @@ module Homebrew
         safe_system "git", "checkout", "-f", "master"
         # This will uninstall all formulae, as long as
         # HOMEBREW_REPOSITORY == HOMEBREW_PREFIX, which is true on the test bots
-        safe_system "git", "clean", "-ffdx" unless ENV["HOMEBREW_RUBY"] == "1.8.7"
+        safe_system "git", "clean", "-ffdx", "--exclude=/Library/Taps/" unless ENV["HOMEBREW_RUBY"] == "1.8.7"
       end
       pr_locks = "#{@repository}/.git/refs/remotes/*/pr/*/*.lock"
       Dir.glob(pr_locks) { |lock| FileUtils.rm_rf lock }
@@ -669,7 +669,7 @@ module Homebrew
         test "git", "clean", "-ffdx"
         HOMEBREW_REPOSITORY.cd do
           safe_system "git", "reset", "--hard"
-          safe_system "git", "clean", "-ffdx"
+          safe_system "git", "clean", "-ffdx", "--exclude=/Library/Taps/"
         end
         if ARGV.include? "--local"
           FileUtils.rm_rf ENV["HOMEBREW_HOME"]