Pages 41-43 of this book
discuss an important narration of Omar that is often taken as evidence by pro-abrogation folks. According to the author, it is rated authentic by Al-Bukhari, and the chain leads to Ibn Abbas attributing the text directly to Omar, may God be pleased with them. I have seen variations of this narration before, but let me translate this version because of its credentials.
Our foremost reciter is Ubayy and our foremost judge is Aly. We indeed leave out from the words of Ubayy as he says he wouldn't leave out a thing that he heard from the Prophet (PBUH), and God has said "Whatever verse We abrogate or cause to be forgotten"
The author goes into detail about how this could mean something other than what it is taken as evidence of, including raising doubts about whether the last sentence was uttered by Omar or by one of the narrators as a commentary.
Authenticity aside, this narration provides no evidence for the abrogation doctrine
, as the subject matter is 'leaving out' rather than annulling, so it would be talking about abrogation of recitation rather than abrogation of ruling and keeping the recitation, the latter being the exclusive subject of the abrogation doctrine as we defined it.
As much as I have doubts about the other types of abrogation, I have to say that those claiming abrogation/forgetting of recitation and ruling stand on a relatively firmer ground than other pro-abrogation claimants.