[dale_glass]

A rebase can be undone, because the old commits keep hanging around in the repo. Rebase doesn't delete or rewrite anything, it just creates new commits and adjusts branch pointers, so the old stuff is still there just hard to get at because nothing points at it anymore.

You just need to find an old commit ID somewhere, normally the reflog.

The old stuff will go away on its own eventually due to git's self-maintenance procedures removing unreachable commits, or it can be done forcefully by adjusting the gc parameters to get rid of it.