On new systems installing any application that uses the D-Bus library will abort with
D-Bus library appears to be incorrectly set up; failed to read machine uuid: Failed to open "/etc/machine-id": No such file or directory See the manual page for dbus-uuidgen to correct this issue.
The reason for this is that ports r347320 removed @postexec dbus-uuidgen --ensure from the plist of devel/dbus to appease Poudriere in strict mode. So the machine-id is never generated until users start the D-Bus service (which not every wants to do) or run dbus-uuidgen --ensure manually afterwards. There are many support request for this on the FreeBSD forums and FreeBSD is also unique in subjecting users to this procedure.
This reintroduces generating the machine-id on install but also whitelists /var/lib/dbus/machine-id in Mk/Scripts/check_leftovers.sh so that Poudriere does not complain about leftover files.
Note that almost any functional FreeBSD desktop must have /var/lib/dbus/machine-id and it must remain the same across package installs/deinstalls so we cannot just track it in pkg-plist via an additional @postunexec.