Which still seems surprising, but so does The Atlantic. This anecdote is one for the books:
[Elizabeth] Bishop, we learn in the new volume of correspondence between the poet and The New Yorker, yielded to most editorial requests, and this time was no different. "It's good to have a standard," said Alice Quinn, formerly the poetry editor at The New Yorker and the caretaker of the Bishop legacy. "Accuracy was one of the three qualities Bishop strove for: accuracy, mystery and spontaneity."
It was copy editors, though, who made their mark on Bishop's most famous poem, changing a colon to a semi-colon in Bishop's "One Art" ("The art of losing isn't hard to master;"), a subtle change that relaxes the statement rather than making it a declaration.
And then there are just screw-ups. At TNR in the old days, we actually published a poem whose final sentence read "This is dummy copy". This boilerplate was a way of fitting words on a page before the final publication and obviously should have been removed before we went to press. It slipped through the copy-editing cracks. The truly tragic thing is that the only reader complaint we got was from the poet himself, who humbly asked why his poem had been so altered.
Yes, we re-ran it the following week, as it should have appeared in the first place.