Darkbot message during "portsdb -u"

[Robert English]

While running "portsdb -u" after making a new index (this has
happened two days in a row now), I get the following message:

/usr/ports/INDEX:3187: darkbot -6f6_r6: 6f6_r6: not in due form:
'<version>[_<revision>] [,<epoch>]'.

It continues from there, and apparently completes without
further incident.  It's a benign issue, at least on my system, 
but I thought it would be a good idea to post an alert about
this to prevent heavier problems further down the road.