What do you think should be done about it? Renaming either seems potentially problematic, although gegl less so.also this is probably something it would be good to take up with geglupstream... installing coreutils with a 'g' prefix is not at all uncommon.
As minimal band-aid, CONFLICTS entries in both packages could alert the user a little bit earlier.
As for a real fix: I don't know. Are there examples, how pkgsrc dealt with this kind of problem in the past? I think, this needs an agreement among the pkgsrc maintainers. I could imagine renaming the gegl one to "gcut-gegl", mainly because it came later and is probably less prone to break scripts already in use that refer to the core-utils version.
Is the "g" prefix really that common? If anybody wants to discuss this with upstream, I think that person should be able to speak on behalf of pkgsrc, so that job is better left to the package maintainer.
-- Jörn Clausen Plattformen & Serverdienste BITS - Bielefelder IT-Servicezentrum