Comment 2 for bug 2039209

> APT::Update::Post-Invoke-Success {

This also implies that the hook is only run because we're doing a fresh 'apt-get update' in each squashfs layer, which we really shouldn't do; if the archive we're building against changes during the build, we should ignore it anyway and keep a single coherent view of the archive for all layers as part of a given build.

the actual call to apt-get update is buried deep in the live-build abstraction, of course.