It would be great if errors related to sets could be more verbose about what sets exactly decided to tip over.
A friend of mine recently hit an error where it reported duplicate sets, and gave the set names, but never said where the sets actually resided.
Information such as the set name, description, and possibly even contained packages would be really handy.
zmedico mentioned adding set support to portageq. This is probably a good idea, but does not necessarily negate the need for better explanations from portage about how exactly to resolve an error.
A bit of discussion about this occurred in another bug: https://bugs.gentoo.org/show_bug.cgi?id=302005#c3
Steps to Reproduce:
Seems this bug is idling in confirmed state. This may be a good project for me to tackle, so if no one else works on this one I might try to attack it.