Socket and unclean exit trouble due to fork(), execve() and exit() interaction

The fork blocks the main network sockets of the primary process and probably does bad things to files and output once the script finishes.

Steps to reproduce: In a server build directory

mkdir -p scripts
echo "" > scripts/noscript
<start server>
SPAWN_SCRIPT noscript

The other side of the bug is that running servers block sockets.

mkdir -p scripts
echo "sleep 9000" > scripts/longtime
<start server>
SPAWN_SCRIPT longtime
<connect with client, leave>

the server will not be able to reclaim its original port after its nap.