Comment by matheusmoreira

Makes sense to me, thank you. It's just something I tried to do once. I didn't think very hard about it so it felt like an arbitrary limitation.

What I tried to do was have two copies of the same branch checked out to a different directory: one pristine, another with uncommitted changes. The idea was to run make on both directories, profile the results and then decide whether to commit or discard the changes. Now I see the solution is to just make another branch.