ngAnimate & ngClass - Does not remove a class that is still animating

[thetrevdev]

Do you want to request a feature or report a bug?
Bug

What is the current behavior?
http://plnkr.co/edit/wsVFlxSJFCslfV9Hossg?p=preview
When a class is added via ngClass then removed too quickly we end up in a state where still have the class on the element.

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem.
http://plnkr.co/edit/wsVFlxSJFCslfV9Hossg?p=preview
*This is a race condition. This plunker is failing over 90% of the time though,

What is the expected behavior?
The falsy ngClass is removed

What is the motivation / use case for changing the behavior?

Which versions of Angular, and which browser / OS are affected by this issue? Did this work in previous versions of Angular? Please also test with the latest stable and snapshot (https://code.angularjs.org/snapshot/) versions.
Plnkr was failing in 1.4 -> 1.5.5

Other information (e.g. stacktraces, related issues, suggestions how to fix)
Definitely related to ngAnimate as the issue goes away when its not used.
Likely related to the intermediate animate states. In the plunker above we would see .background-add on the element at the time we try to remove .background
This appears to only happen when the new ngClass state is also adding classes.

[Narretz]

Thanks for the report. I can reproduce the bug. However, I only see the bug when the classes are initially set in rapid succession. I also only see this behavior when there's 15 ms or less between each update. Such short intervals are pretty unusual, under which circumstances is this happening for you?

[thetrevdev]

It happens pretty frequently for us.
We have an ngClass that would look like { classA: someBool, classB: !someBool }
someBool is getting updated via an api call. It would appear that the api call is coming in right after our element compiles.