crypttab precheck & tmp options not working on 16.04

[Adam Funk]

I did a successful clean installation of 16.04 & left a few partitions
free for encrypted swap and /tmp.  Swap is working fine, but this line
in /etc/crypttab

etmp  /dev/disk/by-id/blah-blah-part6  /dev/urandom  precheck=/bin/true,tmp=ext4

is throwing these errors at boot

systemd-cryptsetup ... Encountered unknown /etc/crypttab option 'precheck=/bin/true', ignoring.
systemd-cryptsetup ... Encountered unknown /etc/crypttab option 'tmp=ext4', ignoring.

so /dev/mapper/etmp doesn't get set up & the boot fails.  Both of
these options are listed in 'man crypttab' --- what's wrong?

Thanks.