diff --git a/app/models/issue.rb b/app/models/issue.rb
index f4ebb2936..725d7dafc 100644
--- a/app/models/issue.rb
+++ b/app/models/issue.rb
@@ -159,7 +159,8 @@ class Issue < ActiveRecord::Base
     end
     send :attributes_without_tracker_first=, new_attributes, *args
   end
-  alias_method_chain :attributes=, :tracker_first
+  # Do not redefine alias chain on reload (see #4838)
+  alias_method_chain(:attributes=, :tracker_first) unless method_defined?(:attributes_without_tracker_first=)
   
   def estimated_hours=(h)
     write_attribute :estimated_hours, (h.is_a?(String) ? h.to_hours : h)
diff --git a/doc/INSTALL b/doc/INSTALL
index 97d9d6080..1f3104644 100644
--- a/doc/INSTALL
+++ b/doc/INSTALL
@@ -7,7 +7,11 @@ http://www.redmine.org/
 
 == Requirements
 
-* Ruby on Rails 2.3.5
+* Ruby 1.8.6 or 1.8.7
+
+* Ruby on Rails 2.3.5 (official downloadable Redmine releases are packaged with
+  the appropriate Rails version)
+  
 * A database:
   * MySQL (tested with MySQL 5)
   * PostgreSQL (tested with PostgreSQL 8.1)