Background:
On enwiki, SineBot adds missing signatures for ips and new users. The bot substitutes a template that notes the comment was unsigned, and includes the editor and the time of the comment. After the template, the bot notes <!--Autosigned by SineBot-->
User story:
As someone using the reply tool,
When I reply to a post that was autosigned by SineBot,
My reply should go after the <!--Autosigned by SineBot--> comment
Example: http://en.wikipedia.org/wiki/Special:Diff/966900777

