update-report: create top-level directories later.

Otherwise if they are created and empty they may be removed again
before we try to create the `/usr/local/bin/brew` symlink.

Library/Homebrew/cmd/update-report.rb

@@ -191,10 +191,6 @@ module Homebrew
       return
     end
 
-    Keg::ALL_TOP_LEVEL_DIRECTORIES.each do |dir|
-      FileUtils.mkdir_p "#{HOMEBREW_PREFIX}/#{dir}"
-    end
-
     new_homebrew_repository = Pathname.new "/usr/local/Homebrew"
     if new_homebrew_repository.exist?
       ofail <<-EOS.undent
@@ -254,6 +250,10 @@ module Homebrew
       EOS
     end
 
+    Keg::ALL_TOP_LEVEL_DIRECTORIES.each do |dir|
+      FileUtils.mkdir_p "#{HOMEBREW_PREFIX}/#{dir}"
+    end
+
     src = Pathname.new("#{new_homebrew_repository}/bin/brew")
     dst = Pathname.new("#{HOMEBREW_PREFIX}/bin/brew")
     begin