merge: tell the user when we are using bid merge Bid merge is a new rarely used feature that the user explicitly enabled - we should tell/warn when the user actually is using it, just like we tell when we not are using it. Give a message like note: merging 3b08d01b0ab5+ and adfe50279922 using bids from ancestors 0f6b37dbe527 and 40663881a6dd