I'd forgotten that the text-only branch of seat_antispoof_msg()
constructs a string from its input in the expectation that it's a
one-line message. So it was a mistake to put a \n at the start of the
string in interactor_announce() to get a blank line first.
Now interactor_announce() makes an extra call to seat_antispoof_msg to
show its blank line, and seat_antispoof_msg itself handles the
blank-line case specially.
028714d02a