bin/52201: mail subject line doesn't display back unicode

[coypu%sdf.org@localhost]

>Number:         52201
>Category:       bin
>Synopsis:       mail subject line doesn't display back unicode
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Apr 29 01:55:00 +0000 2017
>Originator:     coypu
>Release:        NetBSD 7.99.67
>Organization:
>Environment:
NetBSD  7.99.67 NetBSD 7.99.67 (GENERIC) #0: Sun Apr  9 02:09:58 UTC 2017  fly@:/home/fly/netbsd/../amd64/../amd64/sys/arch/amd64/compile/GENERIC amd64

>Description:
$ locale
LANG=""
LC_CTYPE="en_US.UTF-8"
LC_COLLATE="C"
LC_TIME="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_MONETARY="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_ALL="en_US.UTF-8"
$ mail fly
Subject: \U+00D7\U+00A9\U+00D7\U+00A9\U+00D7\U+00A9\U+00D7\U+00A9


Other parts manage.
Would love to see normal characters.
>How-To-Repeat:

>Fix: