Don't resolve fork relationships for projects pending delete

app/models/forked_project_link.rb

 class ForkedProjectLink < ActiveRecord::Base
-  belongs_to :forked_to_project, class_name: 'Project'
-  belongs_to :forked_from_project, class_name: 'Project'
+  belongs_to :forked_to_project, -> { where.not(pending_delete: true) }, class_name: 'Project'
+  belongs_to :forked_from_project, -> { where.not(pending_delete: true) }, class_name: 'Project'
 end