Documentation says that if you exit 0 in a pkg_postinst it will marked as
installed.
If you exit 0, before running postinst-intercepts defer_to_first_boot, the
pkg_postinst_ontarget script will not be present on target.
The "exit 0" in tzdata makes it difficult to have a bbappend with a
pkg_postinst_target step when you have `INSTALL_TIMEZONE_FILE = 0`