update-report: also migrate Caskroom.

Library/Homebrew/cmd/update-report.rb

@@ -231,8 +231,12 @@ module Homebrew
       FileUtils.cp_r "#{HOMEBREW_REPOSITORY}/Library/Taps", "#{new_homebrew_repository}/Library/Taps"
     end
 
+    if (HOMEBREW_REPOSITORY/"Caskroom").exist?
+      FileUtils.cp_r "#{HOMEBREW_REPOSITORY}/Caskroom", "#{new_homebrew_repository}/Caskroom"
+    end
+
     unremovable_paths = []
-    extra_remove_paths = [".git", "Library/Locks", "Library/Taps",
+    extra_remove_paths = [".git", "Library/Locks", "Library/Taps", "Caskroom"
                           "Library/Homebrew/cask", "Library/Homebrew/test"]
     (repo_files + extra_remove_paths).each do |file|
       path = Pathname.new "#{HOMEBREW_REPOSITORY}/#{file}"