Yes, you're correct. It took too long for the release of git plugin 4.0.0, git client plugin 3.0.0, and for the update of this issue. I lost track of this issue report in all the other work that was being done for git client plugin 3.0.0 and git plugin 4.0.0.
I made many mistakes in the long period that was the development of git plugin 3.0.0 and git client plugin 4.0.0. One of the mistakes was assuming that we had a solution for a particularly challenging problem (JENKINS-19022). I spent months exploring that problem, testing alternatives, and testing the changes. I thought it was solved. Then a release was inadvertently delivered to the public which showed within 2 weeks of its release that I was wrong. That change was reverted and then a beta period was started for what would become git plugin 4.0.0.
Thankfully, git plugin 4.0.0 has shown to be reliable, as have 4.1 and 4.2. The upcoming 4.3 release will have larger changes than were included in 4.1 or 4.2.
We'd love to have your help reviewing git plugin pull requests, reviewing git client plugin pull requests, mentoring others as they assist with plugin development, and testing release candidates.
The git client plugin upgrade from 2.x to 3.0.0 was further complicated by a breaking API change in the transition from JGit 4.x to JGit 5.x. The Jenkins git client plugin intentionally bundles JGit so that other plugins can depend on it. The Jenkins compatibility expectations are different than the JGit compatibility expectations, so callers to git client plugin had to be upgraded and released before git client plugin could be upgraded and released. All sorts of interesting things in the release period. And, yes, it took a long time to update this issue report.