There is a way to spawn there, usually involving the "Waiting for Server Response" screen. I've had it happen to me before, and sometimes the Debug Forest can load other players there from the map without them actually being there. They can fire their guns, throw flares and chemlights without actually being there...it's weird. In my experience, I was confused and didn't have a clue where I was on a nighttime server(I had logged out initially at the NW Airfield). Suddenly a flare was thrown next to me that I did not throw. This flare was actually thrown from my friend, but since he was out at the beach spawns he had no clue what I was talking about. After asking multiple times and confirming it was probably none of us I fired and killed the target standing near the flare. Turned out it was my friend all along and the game had created a doppelganger of him in the forest that could fire his gun, etc. The Debug Forest is a very strange place. If you spawn there, the best thing to do is to run directly East or Southeast. Same with the Debug Plains, just run East or Southeast.