Interesting, didn't know that. They mentioned logs like bootstrap.log and dpkg.log, which I noticed, but looking at my shell scripts now there is also nondeterminism/host influence in:

  etc/resolv.conf
  var/cache/ldconfig/aux-cache
  var/lib/urandom/random-seed
  etc/init.d/.depend.{stop,start,boot}
  etc/shadow
  etc/passwd- and family (with trailing hyphen)
  etc/apt/trustdb.gpg and other keys

(not exhaustive)