This plugin is hosted on github
The TicketRelations plugin enables you to define dependency relations between tickets. TicketRelations is based on mastertickets by Noah Kantrowitz but removes the extra fluff (graphs) that came with mastertickets. The concept is the same, in that you define ticket relations using the custom ticket fields blocking and blocked by. TicketRelations is made for and tested on Trac 0.12. I have no idea if it works on older versions.
Installation and configuration
To enable TicketRelations, add the following to trac.ini:
[components] ticketrelations.* = enabled [ticket-custom] blocking = text blocking.label = Blocking blockedby = text blockedby.label = Blocked By
I prefer if you use githubs issue tracker!