needs_full_build() compared mtimes of VERSIONS/package-lists/hooks against
a marker file, which is fragile: a failed build attempt never touches the
marker, and git checkouts/rsync can reorder mtimes relative to real edit
order. This let the fast-path silently reuse a stale squashfs (baked
against old package pins) with no error — root-caused after a driver/DCGM
pin change (590/DCGM 4.6.0 -> 580/DCGM 4.5.2) produced a ~290MB larger ISO
that only shrank back down with --clean-build.
Switch to a content hash (VERSIONS + package-lists + hooks + archives +
bootloaders + auto/config + Dockerfile) instead of mtimes, and add a real
version check in validate_iso_nvidia_runtime: extract dpkg status from the
squashfs and confirm the installed datacenter-gpu-manager-4-core version
matches DCGM_VERSION. The previous check only confirmed dcgmi/nv-hostengine
/dcgmproftester exist, which stays true across DCGM versions and can't
catch this class of staleness.
Mikhail Chusavitin
d2dd305c54