fixed issues does not traverse branches

[DaanHoogland]

inApache CloudStack we have a last release 4.17.20 on branch 4.17 and a new release 4.18.0.0 on branch main/4.18. From the 4.17 branch a bunch of PRs have been merged forward before 4.17.2 and a bunch after. In addition to that a bunch of featured had been developped in parallel to 4.17 fix releases 4.17.1 and 4.17.2. Now the ones that should be included are on main btween 4.17 root and 4.18 root but not on 4.17 before 4.17.2.0. There are two solutions to this:

1. calculate both lists and generate a delta
2. retrieve the issues marked as milestone 4.18.0.0 (we did do prudent tagging of milestones)

both have their own challenges. I am looking into what is the best solution but ant clues are welcome.