Redmine

UseCase:
2 Production Branches, 1 Trunk
Customer submits bug for branch one. After analysing it is decided to also fix the bug in branch two and trunk.
So you have to merge or redo the bugfixing in 2 other releases.
That means you need a referenz for planing, development, time booking and testing for the other two releases.
It would be nice to have a copy to diffrent version feature where you could choose the target versions.
But more important there should be a relation wich represents that it was copy from the original in another version not only that it is related. Maybe nice if Bug number stays the same and is identified with issue + Version number