Messing up conflicts during a rebase, thinking I did it right, and then finalizing the rebase and losing work that accidentally disappeared. That's my most common mistake at least.
> If "loosing your work and it's not in the git log" isn't an exceptional case, what exactly is a "exceptional case"?
Losing your work should be exceptional. It's very, very easy to fuck a rebase up, and rebasing is (like it or lump it) a common operation. You shouldn't one step away from an exceptional case from a daily operation.