{4} = IssueID from issue tracker integration..

This further enables the previous request to add Branch Name as an option... for the same purpose, CI servers that can integrate with issue management system.

https://plasticscm.uservoice.com/forums/15467-general/suggestions/6821986-to-extend-the-custom-comments-auto-text

My issue tracker branches are prefixed like "yt_TICKET-2" and that won't match on my CI server as it expects issue id "TICKET-2" instead..