You described it quite well, that is a b*tch post.
If you compare it to my post however, you can clearly see I'm not b*tching about anything, only making a suggestion how to improve and presenting a concept.
Well, first of all, I don't wanna be a dick but if you think the top comment is much funnier than the post itself, why wouldn't you just like the top-comment? Because who knows, if everyone just likes the post when the comments funny, the top comment may even change over time..
But also I have to say you're right, repost_topcomment ≠is_repost also is a possibility, but I think you would only like repost_topcomment if you also think you saw that post before. So, If a troll just writes repost_comment, people (to some degree hopefully) won't like it just that it's gets repost_topcomment instead of repost_comment, but only if they also think they saw that post before on HL, which will ensure us that repost_comment will only equal repost_topcomment if a big number of people are sure that the post a repost, so is_repost is a very high possibility.
Additionally, if there is no repost_comment or repost_topcomment, but is_repost, normal report function can still get used.
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