Game mode override isn't working when rendering a Sequence

Game mode override isn't working when rendering a Sequence

Regression: YES

Working: 4.14 Release CL:3164219
Broken 4.15 Dev-Sequencer CL:3164583

1. Create a third person project
2. Create a Master sequence with 2 shots
3. Make a gap between the two shots
4. Render Movie
5. Ensure Game Mode override is set to GameMode
6. Render

Result: In the gap between the two shots, the Third Person Pawn and game mode are used
Expected: GameMode is used (just a camera with no character)