(I don't think bug 1572247 is a proper blocking bug because it widely affects on all other platforms though)

In bug 1606503 we've noticed that gtk-enable-animations on our new ubuntu18.04 machines is enabled by default (whereas it seems the setting is disabled by default on ubuntu16.04). The gtk-enable-animations affects prefers-reduced-motion media query feature. Emilio noticed me in a review comment that there may be some test cases that are not properly tested as expected on the new ubuntu18.04 machines and I totally agree.

Note that in bug 1606503 the test in question fails on race conditions so there may be various patterns, "failed intermittently" or "success but should fail", etc.

:hiro - thanks for the bug.

My understanding is a bit sketchy at best, but as someone responsible for the migration from ubuntu1604 to ubuntu1804, should I be switching this setting on ubuntu1804 to disabled to mimic the behavior on ubuntu1604?

For context, my aim is to replicate the desktop environment of the end user as much as possible with the ubuntu1804 image, which was something the old ubuntu1604 image fell short of in some aspects, most notably the window manager (using compiz instead of unity). Given that you state this setting appears to be set to enabled by default on ubuntu1804, is it advisable to keep it that way?

Edwin, I believe you've been doing right things to do. The problem I want to make sure in this bug is that automated tests should run on environments whatever the system's initial values are. So, at least the test in bug 1606503 has a flaw in test itself, and I think if there are any other tests having similar issues, those tests should be modified to be able to run on any environments.