Trouble setting LC_CTYPE in a pared down chroot

["John Marino (NetBSD)" <netbsd%marino.st@localhost>]

I've put together a system root based on a minimalist subset of the
NetBSD 9.2/AMD64 release.  It's working fine except for one small
problem with locales.

These are the complete contents of /usr/share/locale in that system root:
usr/share/locale/en_US.UTF-8/LC_MONETARY
usr/share/locale/en_US.UTF-8/LC_NUMERIC
usr/share/locale/en_US.UTF-8/LC_TIME
usr/share/locale/en_US.UTF-8/LC_MESSAGES/SYS_LC_MESSAGES
usr/share/locale/en_US.UTF-8/LC_CTYPE

This is the result of the attempt to set to the en_US.UTF-8 locale:

# env LANG=en_US.UTF-8 ./locale
LANG="en_US.UTF-8"
LC_CTYPE="C"
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=""


The LC_COLLATE being left at the C locale is normal, I believe.
However, the loading of LC_CTYPE is failing silently.  I've tried
going through the source.  I'm sure it's some file that needs copying
into the system root, but I can't figure out which file that is.  It
doesn't appear to be documented.  The LC_CTYPE appears to have a
different mechanism (runes) for loading than the other categories.

Is there anyone really familiar with the NetBSD locale system that
knows why LC_CTYPE is being ignored inside the chroot?  I've spent a
lot of time on this, so it's probably time for me to ask for some help
here.

Thanks,
John