bin/54343: "man -k config | less" broken

[Thomas Klausner <wiz%NetBSD.org@localhost>]

>Number:         54343
>Category:       bin
>Synopsis:       "man -k config | less" broken
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Jul 04 19:25:01 +0000 2019
>Originator:     Thomas Klausner
>Release:        NetBSD 8.99.47
>Organization:
Curiosity is the very basis of education and if you tell me that
curiosity killed the cat, I say only that the cat died nobly.
- Arnold Edinborough
>Environment:
Architecture: x86_64
Machine: amd64
>Description:
man -k config

spams the screen.
So I tried redirecting it through less, but then I get nothing.

I also tried
man -k config 2>&1 | less
because I thought it might be written to stderr, but that didn't work either.
>How-To-Repeat:
see above
>Fix:
I suggest so, yes.

>Unformatted: