To reproduce:
1. Open attached project;
2. Open "Test" scene;
3. Choose "Hero" game object in the hierarchy;
4. In the Animation window, choose "FoorFar : Rotation";
5. Change Dopesheet to Curves in the Animation Window;
6. Select a point further in the timeline;
7. Start recording the animation;
8. Rotate the object with a rotation gizmo in the Scene view while looking in the Curves window.

Expected result: no animation curve stuttering.
Actual result: curve is stuttering in the Animation window while rotating the game object.

Note: didn't notice any animation curves stuttering while rotating 3d objects.

Forum thread: https://forum.unity3d.com/threads/rotation-curve-twisting-and-flipping-gimbal-lock.468594/

Reproduced on versions: 5.5.4p1, 5.6.2p1, 2017.1.0f1, 2017.2.0b1.

Fixed and verified on: 5.6.3p2, 2017.1.0p3, 2017.2.0b5, 2017.3.0a1.