Bug 376997 breaks every transparent image that doesn't explicitly set a background color and assumes the default is white. (i.e. all of them) This includes about:logo. The text is now dark grey on dark grey, making it almost unreadable (and ugly).

about:logo isn't exposed to users in any significant way, and this only applies to non-official branding, so I don't think we need to bother trying to fix it.

Shouldn't we remove it, then? Including broken features, even if not user-visible, makes little sense.

You can file a bug about that, sure. It's been around for a long time and is used in some tests, so it'd probably be more trouble than it's worth.

It's also the image used in about: