Fix lost backward compatibility about ProjectQuery#results_scope's re…

…turn type

app/models/project.rb

@@ -382,6 +382,7 @@ def reload(*args)
     @override_members = nil
     @assignable_users = nil
     @last_activity_date = nil
+    self.class.clear_last_activities
     base_reload(*args)
   end
 
@@ -1009,18 +1010,16 @@ def visible_custom_field_values(user = nil)
     end
   end
 
-  def last_activity_date
-    @last_activity_date || fetch_last_activity_date
+  def self.last_activities
+    @last_activities ||= Redmine::Activity::Fetcher.new(User.current).events(nil, nil, :last_by_project => true).to_h
   end
 
-  # Preloads last activity date for a collection of projects
-  def self.load_last_activity_date(projects, user=User.current)
-    if projects.any?
-      last_activities = Redmine::Activity::Fetcher.new(User.current).events(nil, nil, :last_by_project => true).to_h
-      projects.each do |project|
-        project.instance_variable_set(:@last_activity_date, last_activities[project.id])
-      end
-    end
+  def self.clear_last_activities
+    @last_activities = nil
+  end
+
+  def last_activity_date
+    self.class.last_activities[id] || fetch_last_activity_date
   end
 
   private

app/models/project_query.rb

@@ -165,12 +165,6 @@ def results_scope(options={})
     if has_column?(:parent_id)
       scope = scope.preload(:parent)
     end
-
-    projects = scope.to_a
-    if has_column?(:last_activity_date)
-      Project.load_last_activity_date(scope)
-    end
-
-    projects
+    scope
   end
 end