wibox.layout.fixed.horizontal does not respect height of smaller widgets

[SystematicError]

Output of awesome --version:

awesome v4.3-1588-gb54e50ad (Too long)
 • Compiled against Lua 5.1.4 (running with LuaJIT 2.1.0-beta3)
 • API level: 4
 • D-Bus support: no
 • xcb-errors support: no
 • execinfo support: yes
 • xcb-randr version: 1.6
 • LGI version: 0.9.2
 • Transparency enabled: yes
 • Custom search paths: no

How to reproduce the issue:

local awful = require "awful"
local wibox = require "wibox"

awful.popup {
    widget = {
        {
            text = "Large text",
            font = "Monospace 22",
            widget = wibox.widget.textbox
        },

        {
            wibox.widget.progressbar
            
            height = 5,
            width = 200,
            widget = wibox.container.constraint
        },

        layout = wibox.layout.fixed.horizontal
    },

    visible = true,
    placement = awful.placement.centered
}

Actual result:

The docs do mention that the forced_height property may be ignored, but even the constraint widget is not respected by the layout. Even if this is intended the user should have the ability to at the very least control the height of smaller widgets somehow, whether it be through respecting wibox.container.constraints or through some "strategy" algorithm, similar to how wibox.container.align implements it.

Expected result:

The progress bar widget should've only been 5 pixels tall as specified, however it instead is the size of the largest widget.