v.random: do not transfer cat from area if attributes are coppied too

[marisn]

trafficstars

Current code creates two cat entries for each point on the same level - one from area point is in and one matching new entry in the database. As entries in db have new cat values, old cat value points to a random or non-existing entry in the db thus causing a mess. Fixes #2475.

[wenzeslaus]

I resolved the conflict in the GitHub web interface by using the new line.