Like the person you replied to, the example makes no sense to me.
I don't program in Rails, but, in the languages that I do/have I don't recall a situation where it was _likely_ that a function or API that replaces something deprecated in an older version, was already available in that older version.
The only case I can think of, that happens regularly, is that something would be deprecated and marked as such, with a replacement available at the point of deprecation.
That deprecated usage should be replaced before it is removed; and if we're talking about skipping multiple major versions over a long period, the replacement likely didn't exist in the older version, so this method still wouldn't work.
I don't program in Rails, but, in the languages that I do/have I don't recall a situation where it was _likely_ that a function or API that replaces something deprecated in an older version, was already available in that older version.
The only case I can think of, that happens regularly, is that something would be deprecated and marked as such, with a replacement available at the point of deprecation.
That deprecated usage should be replaced before it is removed; and if we're talking about skipping multiple major versions over a long period, the replacement likely didn't exist in the older version, so this method still wouldn't work.