--- redmine.orig/lib/redmine/plugin.rb
+++ redmine/lib/redmine/plugin.rb
@@ -47,7 +47,7 @@ module Redmine #:nodoc:
     self.directory = File.join(Rails.root, 'plugins')
 
     cattr_accessor :public_directory
-    self.public_directory = File.join(Rails.root, 'public', 'plugin_assets')
+    self.public_directory = ENV['RAILS_TMP'] ? File.join(ENV['RAILS_TMP'], 'plugin_assets') : File.join(Rails.root, 'public', 'plugin_assets')
 
     @registered_plugins = {}
     class << self