IssueTracker

Initially I found that bug in framework version of Transitions. I think it will be great to fix the issue in Support Library Transitions as well to have consistent behaviour.
Original bug:
https://code.google.com/p/android/issues/detail?id=222602

Example project to reproduce: https://github.com/andkulikov/SupportSceneWithNullTransitionBug/

How we can fix it for 4.4+? For example we can provide like empty transition instead of null and it will be handled properly
https://gist.github.com/andkulikov/21cec7500aa6f47c314aaa99f2238232

And for preKitkat there are two issues:
1) If we will provide null it crash because in TransitionManagerPort method private static void changeScene(ScenePort scene, TransitionPort transition) there are no check for null for transitionClone before transitionClone.setCanRemoveViews(true) call.
It was fixed in the framework here https://android.googlesource.com/platform/frameworks/base/+/5a7cf3eeeb208c2dac52541cb09b519b4342a5ff
2) There are no sPendingTransitions.add(sceneRoot) for scene changes case at all. We should have the same checks as in framework version.
Fix in framework:
https://android.googlesource.com/platform/frameworks/base/+/96e54dcfa4e2f5295b0441971f10906eeaa35328%5E%21/#F0
and after that not to forget remove it from sPendingTransitions in sceneChangeRunTransition if transition is equal null via sPendingTransitions.remove(sceneRoot); - (that thing was an original bug https://code.google.com/p/android/issues/detail?id=222602)


I've already fixed the issue in my backport of transitions framework - https://github.com/andkulikov/Transitions-Everywhere