[faiproject/fai] 272652: set TMPDIR for chroot, Closes: #1000572

[Mrfai]

  Branch: refs/heads/master
  Home:   https://github.com/faiproject/fai
  Commit: 2726525da7fbcd73ff5e949516890fa80ffb6783
      https://github.com/faiproject/fai/commit/2726525da7fbcd73ff5e949516890fa80ffb6783
  Author: Thomas Lange <lange at debian.org>
  Date:   2022-01-02 (Sun, 02 Jan 2022)

  Changed paths:
    M bin/fai-cd

  Log Message:
  -----------
  set TMPDIR for chroot, Closes: #1000572