Portsnap fetch fails in RaspBSD 12 on RPi3

First I couldn't run 'portsnap fetch' due to the system time being off.
Snapshot appears to have been created more than one day into the future!
(Is the system clock correct?)
Cowardly refusing to proceed any further.

Setting the time using the command 'ntpdate' fixed that issue, but got me a new instead:
Verifying snapshot integrity... Segmentation fault (core dumped)
snapshot corrupt.

This can be worked around by manually installing the ports tree.
wget http://ftp.freebsd.org/pub/FreeBSD/ports/ports/ports.tar.gz
tar xvf ports.tar.gz -C /usr/

Sources:
FreeBSD documentation - using ports
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