Android srcset bad craziness

Apparently a bunch of Android devices poop all over <img srcset>. I'm seeing nonsense in my logs where Android is trying to load the srcset as if it was src, e.g. from here it's doing:

GET /images/2017/inhuman-drywall1.jpg%20711w,%20https://www.jwz.org/images/scaled/640/2017/inhuman-drywall1.jpg%20640w,%20https://www.jwz.org/images/scaled/360/2017/inhuman-drywall1.jpg%20360w HTTP/1.1

The user agents look like

"Dalvik/2.1.0 (Linux; U; Android 8.0.0; Pixel XL Build/OPR3.170623.008)"

and so on, with the version going down to 6.0.1.

But when I run an Android emulator, it has a more traditional user agent beginning with "Mozilla/5.0 (Linux; Android 8.0.0".

What is that other crap? And how is it so broken?

Update: The prime offender here seems to be NewsBlur, both their web site and their mobile apps. Several NewsBlur users have reported this bug to them, but they haven't done anything about it, so I guess I'll just start blocking them until they fix it.

Previously, previously.