Can't set notification borders with theme.notification_border_width and theme.notification_border_color #3786

Output of awesome --version:

awesome v4.3-1588-gb54e50ad6 (Too long)
• Compiled against Lua 5.4.4 (running with 0.9.2)
• API level: 4
• D-Bus support: yes
• xcb-errors support: no
• execinfo support: yes
• xcb-randr version: 1.6
• LGI version: /usr/share/lua/5.4/lgi/version.lua
• Transparency enabled: yes
• Custom search paths: no

How to reproduce the issue:

Copy the default theme.lua in /usr/share/awesome/defaults to ~/.config/awesome, and add the following lines after -- Variables set for theming notifications::

theme.notification_border_width = 6
theme.notification_border_color = "#000000"

Modify the beautiful.init(...) line in rc.lua to beautiful.init("~/.config/awesome/theme.lua").

Run notify-send "test" in terminal.

Actual result:

No border appears for the notification window.

Expected result:

The notification window would have a black border.