Quoting Trent W. Buck (trentbuck@gmail.com):
FWIW I've rejected trn/trn4 because Debian puts it in non-free, and I'd rather not enable non-free.
Yeah, you see, I never even noticed that, because the last time I even looked at trn was around 1994 and I was running Slackware. Back then, most of us hadn't yet learned to be wary of licensing problems. trn's licensing (now that I bother to look at it) is one of those 'gratis for non-commercial use only' licences that were common among source-available packages in the 1980s/1990s. Debian's licensing notes include this: The author of trn, Wayne Davison, has expressed a desire to eventually relicense it under the BSD licence (minus the advertising clause). Unfortunately, this will have to wait until certain old code from other sources is removed.