This is a followup to e0ade40c2b7f39dc109ef03d43241033e14c4d4a, which didn’t have the desired effect. * gnu/services/virtualization.scm (virtual-build-machine-default-image): Add ‘volatile-root?’ field. Change-Id: I1a622f22cdd0f8f83860a6eb4a852518db3b46b7