The behaviour of uncommit may confuse a new user. Although it never
destroys the data, it can hide instead. I added a `-f/--force` flag
when the working copy is dirty. The data can be visible on `--hidden`
Some cases in `test-uncommit.t` changes output. I'll be working on
this further based on review.
Original patch to evolve extension authored by Dan Villiom Podlaski Christiansen: