Steps to reproduce:
1. Open attached project.
2. Open scene named "main".
3. In the "Hierarchy" window try searching for a word "gameobject".
4. Select one of game objects that were found by searching, drag and drop them to the prefab inside of the "Assets" folder.
5. Notice that this action cannot be performed.

Expected result:
User should be able to drag and drop game object found by using a search bar without exiting search mode.

Reproduced with:
5.3.1f1, 5.3.4f1, 5.3.4p6, 5.4.0b18.

Cannot reproduce with:
5.1.0f3, 5.2.4f1.