Bugzilla imposes a column-width limit, which usually makes it nicer to read paragraphs of text:

However when comments contain logging output including stack traces, the automatic wrapping can make it much harder to follow, e.g.:

So I wrote a tiny script that may be used with Tampermonkey (and probably other similar extensions), which makes Bugzilla use the full browser width:
// ==UserScript==
// @name Wide Bugzilla
// @namespace http://tampermonkey.net/
// @version 0.1
// @description Make Bugzilla use the full browser width
// @author Gerald Squelart
// @match https://bugzilla.mozilla.org/show_bug.cgi?*
// @grant none
// ==/UserScript==
(function() {
'use strict';
document.getElementById("main-inner").style.maxWidth = "100%"
})();
Assuming your screen is wide enough, the log is now much more readable:

If you don’t want to use Tampermonkey or similar, you may just open a Javascript console and enter document.getElementById("main-inner").style.maxWidth = "100%"
for the same effect on the current page.
And of course, you could always copy the log to your favorite non-wrapping editor. 😉