Andy Warhol, anyone? Campbell Soup cans? Marilyn?
Re-reading the thread, I’m not seeing any consensus developing whatsoever, nor any agreement on geography or as to what constitutes “a” and “painting”.
There doesn’t need to be “agreement” for something that already has a definition, like painting. Sure, there might not be bright-line differentiation between, say, drawing and painting (we could have a whole thread for that - what are pastels to you, and why?) but there is no relevant definition of “painting” that includes The Great Wave off Kanagawa or 32 Campbell’s Soup Cans, or Vitruvian Man - really any person advocating for those as “paintings” would just be being bolshie. “Work of art” =/= “painting”
“a”, of course, we could argue about (and should!), although I’d say it’s OK to include all close copies if the image itself is what people recognize, like The Scream should be considered “a painting” for this sort of discussion because though there are multiple versions, and prints, when hoi polloi say “The Scream” it’s almost a certainty a reproduction of the Oslo National Gallery one they’ve seen and are thinking of. But “Van Goghself-portrait” is not “a painting” and requires more specificity (even my earlier Portrait with a Bandaged Ear wasn’t specific enough - I meant Self-portrait with Bandaged Ear, Easel and Japanese Print. Good thing I didn’t go with Portrait with A Straw Hat 
).
I really don’t see a sense in which that work is not a painting. They’re literally drawn (the underdrawing) and hand-painted. Even MOMA refers to the works as “paintings.”
I’d read contradicting material that said the base cans were silkscreened, then overpainted. But I’d happily take MOMA’s word on this.