While debugging something else I observed that latest `main` ignores
`Control-C` on `sudo nix-build`.
After reading through the capnproto docs, it seems as if the promise
must be fulfilled to actually terminate the `promise.wait()` below.
This also applies to scenarios such as stopping the client
(`nix-build`), but the builders on the daemon-side are still running,
i.e. closes#540
Co-authored-by: eldritch horrors <pennae@lix.systems>
Change-Id: I9634d14df4909fc1b65d05654aad0309bcca8a0a