@issue.author = User.current という行の後ではなくて
@issue.safe_attributes = params[:issue] の行の後に入れるとよさそうです。
--- app/controllers/
issues_controller.rb.org+++ app/controllers/issues_controller.rb
@@ -408,6 +408,7 @@
end
@issue.start_date ||= Date.today if Setting.default_issue_start_date_to_creation_date?
@issue.safe_attributes = params[:issue]
+ @issue.assigned_to ||= User.current
@priorities = IssuePriority.active
@allowed_statuses = @issue.new_statuses_allowed_to(User.current, true)