UserAgent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:62.0) Gecko/20100101 Firefox/62.0

Example URL:

Steps to reproduce the problem:
$ chromium-browser --headless --log-net-log=netlog.json --screenshot http://www.amazon.com
$ ls -la netlog.json 
-rw------- 1 atrox atrox 29586 Sep 16 01:06 netlog.json
$ wc -l netlog.json 
2 netlog.json

While the netlog is truncated to unusability, the screenshot produced is fine.

What is the expected behavior?
if you call chrome/chromium in UI mode, and close the window after page load:
$ chromium-browser --log-net-log=netlog.json http://www.amazon.com
$ ls -la netlog.json 
-rw------- 1 atrox atrox 1610969 Sep 16 01:07 netlog.json
$ wc -l netlog.json 
13168 netlog.json

What went wrong?
It worked in chrome 66 and 67, but does not with chrome 69 nor chromium 69.

Did this work before? N/A 

Chrome version: 69.0.3497.81  Channel: n/a
OS Version: 
Flash Version: Shockwave Flash 31.0 r0