Unsupported locale errors in XOrg

[Prashanth Chandra]

Hello,

I'm getting "unsupported locale" warnings and crashes when running
programs such as xterm or dmenu on a clean install of Ubuntu 17.10

Examples:
warning: no locale support
Warning: locale not supported by Xlib, locale set to C

Here's the offending line from dmenu's source code:

if (!setlocale(LC_CTYPE, "") || !XSupportsLocale())
fputs("warning: no locale support\n", stderr);

I'm not 100% sure but I was told that this looks like an issue in XOrg.
Additionally, the problem disappears if I change my default locale to
en_US.UTF-8 instead of en_HK.UTF-8, which suggests that the issue is
specific to my locale.

Here's the output of running locale:

LANG=en_HK.UTF-8
LANGUAGE=en
LC_CTYPE="en_HK.UTF-8"
LC_NUMERIC="en_HK.UTF-8"
LC_TIME="en_HK.UTF-8"
LC_COLLATE="en_HK.UTF-8"
LC_MONETARY="en_HK.UTF-8"
LC_MESSAGES="en_HK.UTF-8"
LC_PAPER="en_HK.UTF-8"
LC_NAME="en_HK.UTF-8"
LC_ADDRESS="en_HK.UTF-8"
LC_TELEPHONE="en_HK.UTF-8"
LC_MEASUREMENT="en_HK.UTF-8"
LC_IDENTIFICATION="en_HK.UTF-8"
LC_ALL=

Here's the output of running locale -a:

C
C.UTF-8
en_HK.utf8
en_US.utf8
POSIX

Would appreciate any pointers in understanding this issue.

Prashanth