bin/54339: sh (or libedit?) pasting oddity

[dholland%NetBSD.org@localhost]

>Number:         54339
>Category:       bin
>Synopsis:       sh (or libedit?) pasting oddity
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jul 02 18:25:00 +0000 2019
>Originator:     David A. Holland
>Release:        NetBSD 8.99.25 (20181103)
>Organization:
>Environment:
System: NetBSD valkyrie 8.99.25 NetBSD 8.99.25 (VALKYRIE) #28: Thu Jan 17 20:46:50 EST 2019  dholland@valkyrie:/usr/src/sys/arch/amd64/compile/VALKYRIE amd64
Architecture: x86_64
Machine: amd64
>Description:

Open an xterm. exec sh, do "set -o emacs". Type
"abcdefgijklmnopqrstuvwxyz ". Hit backwards-word and cut this string
with ^K, then paste it with ^Y repeatedly. After 37 pastes (if I
counted right) further pastes do not go but beep instead.

Type a few characters, then try ^Y again. It will beep. Type a few
more after that (18 total seems to be enough here) and then ^Y; it
will paste. Repeat pasting, and after a bunch more pastes the same
thing happens. Type some more, and you can paste again. Repeat,
apparently, indefinitely, until you get tired of watching libedit get
confused by lines longer than the screen.

This seems strange. Is the input line length supposed to be limited,
or not?

>How-To-Repeat:

>Fix: