Hello Erik,
Roland: With git, it shouldn't matter in what repository a branch lives. Feel free to give your branch names such as "rhaas/experiment9", "rhaas/useful-but-rejected" and push them to the main Carpet repository. Or choose these names and keep them in your local repo, pulling in the main Carpet repo. In the end, it's just the working directory where you make changes, and a branch in some repo where you can push and pull if needed.
The rearrangement of thorns removes WaveToyMoL and IDWaveToyMoL. I believe those were the only examples using MoL so it may be good to move them into say CactusWave (needs change in license probably).
Yours, Roland