Had the case of having to move and combine 4x large trac repositories into a single redmine systems. In this process ended up enhancing the trac migration a handle wiki text better and allow multiple loads from same source to pick up changes.

Only real hack as needed to keep old trac ticket references visible so added a external_ref field to issues table. Could not use id as moving
lots of tickets with same id and also needed to repeat a number of times to got sign off to full move.

I have attached the altered rake task