[MIG] Migration of account_renumber to 8.0.

@sbidoul, @pedrobaeza, @guewen : I was kinda sure there was a good reason for the observation. Maybe just a comment without a rejection would have had the same illustrative effect without a work load increase. Your word *slightly* is the key point for me, but I'll abide the decision. And, of course, I'll take note of your observations.

I'll change this ASAP, thank you both for your comments.