Breaking change in local_connection: passing list(conn) used to work

[MichaelChirico]

Noticed when updating from 2.5.1 to 3.0.1 today, this example started failing:

writeLines('a', tmp<-tempfile())

local({
  local_connection(list(file(tmp, open='r')))
  NULL
})

I think the new error is good and AFAICT we've always been using local_connection() incorrectly.

However, I expected to find some mention in the NEWS by searching "connection" to steer me in the right direction, to no avail. OTOH, I don't see any change in the local_connection() source code, so maybe this is due to a change in defer()? Still it's not clear to me what's changed from glancing at the NEWS, so I'm filing this issue.