Steps to reproduce (or just watch mp4):
1. Open my attached project.
3. Open "rotation_attempt" scene.
4. Press hand object in hierarchy menu.
5. Open "Animation" view.
6. Add rotation property.
7. Move the time line to ~0:30
8. In the toolbar use rotate tool to rotate object (make sure animation record mode is on).
--- Changing rotation values in inspector doesn't reproduce this issue.
9. In animation window move time line a bit and come back to previous position.
--- Notice that values has changed.

Reproduced with: 5.4.0f1, 5.4.0b25, 5.4.0b23, 5.4.0b22, 5.4.0b21.
Not reproduced with: 5.4.0b20, 5.3.5p8, 5.2.0f3.
Regression introduced in : 5.0.b21
Workaround: Use inspector to change values.