[TF2] Signon buffer overflow when loading map with Maxplayers 1

[funniman-exe]

In the TF2 Client/Server branch, loading into almost any map results in the following error message:
Host_Error: Signon buffer overflowed 10 bytes!!!
The amount of bytes varies for whatever reason.

Apparently some folks have gotten certain maps to load successfully, but in my experience every single map I've tried encounters this error.

This behaviour seems consistent whether cl_localnetworkbackdoor is enabled or not.

Something to note; this issue only occurs with the TF2 Client/Server code, not the HL2MP code. Meaning that something the TF2 Client/Server does is causing overflow issues with the Signon buffer. It's also worth mentioning that the Signon buffer is engine side, so if it's an issue with the Signon buffer itself then we're at a loss.