Avoid calling attr_protected if _accessible is used

When attr_accessible is used, we may assume that watcher_ids and
watcher_user_ids is already protected from mass assignment. Therefore we do not
need to perform additional actions.

Also, when attr_protected and attr_accessible is used on the same model, AR
throws nasty "Declare either attr_protected or attr_accessible for *, but not
both." errors.

vendor/plugins/acts_as_watchable/lib/acts_as_watchable.rb

@@ -3,24 +3,24 @@
 module Redmine
   module Acts
     module Watchable
-      def self.included(base) 
+      def self.included(base)
         base.extend ClassMethods
-      end 
+      end
 
       module ClassMethods
         def acts_as_watchable(options = {})
-          return if self.included_modules.include?(Redmine::Acts::Watchable::InstanceMethods)          
+          return if self.included_modules.include?(Redmine::Acts::Watchable::InstanceMethods)
           send :include, Redmine::Acts::Watchable::InstanceMethods
-          
+
           class_eval do
             has_many :watchers, :as => :watchable, :dependent => :delete_all
             has_many :watcher_users, :through => :watchers, :source => :user, :validate => false
-            
+
             named_scope :watched_by, lambda { |user_id|
               { :include => :watchers,
                 :conditions => ["#{Watcher.table_name}.user_id = ?", user_id] }
             }
-            attr_protected :watcher_ids, :watcher_user_ids
+            attr_protected :watcher_ids, :watcher_user_ids if accessible_attributes.nil?
           end
         end
       end
@@ -29,38 +29,38 @@ module Redmine
         def self.included(base)
           base.extend ClassMethods
         end
-        
+
         # Returns an array of users that are proposed as watchers
         def addable_watcher_users
           self.project.users.sort - self.watcher_users
         end
-        
+
         # Adds user as a watcher
         def add_watcher(user)
           self.watchers << Watcher.new(:user => user)
         end
-        
+
         # Removes user from the watchers list
         def remove_watcher(user)
           return nil unless user && user.is_a?(User)
           Watcher.delete_all "watchable_type = '#{self.class}' AND watchable_id = #{self.id} AND user_id = #{user.id}"
         end
-        
+
         # Adds/removes watcher
         def set_watcher(user, watching=true)
           watching ? add_watcher(user) : remove_watcher(user)
         end
-        
+
         # Returns true if object is watched by +user+
         def watched_by?(user)
           !!(user && self.watcher_user_ids.detect {|uid| uid == user.id })
         end
-        
+
         # Returns an array of watchers' email addresses
         def watcher_recipients
           notified = watcher_users.active
           notified.reject! {|user| user.mail_notification == 'none'}
-          
+
           if respond_to?(:visible?)
             notified.reject! {|user| !visible?(user)}
           end