[Flimm]

In fact, I solved that level using only 'git revert' commands, which I don't think was the intended solution. And the displayed solution isn't complete: it asks the user to perform an interactive rebase. (I'm not complaining, just feedback.)

[xxbondsxx]

That's a good point. I should just disable revert in all levels except for those related to it. I rarely revert in practice so it's not a huge issue.

Showing the concept of a "modified" commit is hard though. That's why I did all the C1' sillyness (like the man pages do). The apostrophes also scale nicely (up to C1'^99) where reverting a reverted rebased commit might make the text too big.

EDIT: Fixed, see: https://github.com/pcottle/learnGitBranching/issues/7