Will Chandler

I should mention that on Windows `fs::canonicalize()` returns the [somewhat unusual UNC format](https://github.com/rust-lang/rust/issues/42869): ``` usercfg:\\?\C:\Users\myuser\AppData\Roaming\jj\config.toml ui.color="auto" ``` The [dunce](https://docs.rs/dunce/latest/dunce/) crate could be used to convert to the more commonly used...

I'm happy to rebase this against `master` if @alexliesenfeld is interested.

> introducing a third closure parameter feels a bit much Thanks @alexliesenfeld, I agree adding an additional parameter is overkill for one option. I'll take a stab at your first...

@alexliesenfeld I've force pushed the update, I didn't think there was any benefit to keeping the original commit around since it was so outdated.