The lix daemon wants to avoid orphan processes outliving a lix build. In order to do that it kills all processes under the build user's UID after and before a build. When using sandboxes under Linux, this is unecessary, as builds are run inside a PID namespace, which guarantees that processes cannot outlive the "init" process. Partially fixes https://git.lix.systems/lix-project/lix/issues/667 Change-Id: Idb2cdaad30169b75d730e8a18b360330516faf8b