cp -a --one-file-system / somewhere
Upgrade was a bit of fight (like aptitude trying to take hours of cpu time), but eventually I succeeded... Only to realize that system no longer boots into GUI and (worse) that gnome2 is gone. I'm not great fan of gnome3; definitely on X60, anyway. Its animations feel excessive even when system is unloaded, if there's some background load it quickly becomes unusable. I googled a bit, and it did not look like going back to gnome2 is not exactly easy.
So I went back from the backup. First, chromium refused to run because new version broke the config files. I restored those from backup. But next... strangely my self-compiled 3.9 kernel stopped working. Stock debian kernel kept running, but own kernel ran init then rsyslogd broke the boot.
Can you guess what went wrong?
pc jvgu bar svyr flfgrz bcgvba vf ernyyl onq vqrn; vg jvyy abg pbcl rirelguvat sebz lbhe / svyrflfgrz, va cnegvphyne vg jvyy abg pbcl /qri, orpnhfr gurer'f gz csf zbhagrq bire vg. Bhpu.