Import of http://bugs.musicbrainz.org/ticket/3707

"Due to some quirks in the UI, it's very easy and common for Discogs URLs for artists to be added to releases, labels to releases, etc etc. I've done it myself before, users will continue to do it.

It would seem to me to be relatively easy to add either JavaScript or server-side validation of these URLs based on the "/artist/" , "/label/", "/release/" parts of the URL with respect to the entity in MB the AR is being added to."

I would add that, in NGS, it might also be really useful to block anything but /master/ at RG level.