I was hosting on r2271 and one client ("sCaR" from Canada) was connected using 3.5.1 (release).
He joined my lobby, then disconnected to change his player name. At this moment I got this message:
[2011-05-20 19:54:20] *ERROR* SOCKET WRITE TIMEOUT In [[redacted]/source/shared_lib/sources/platform/posix/socket.cpp::isWritable Line: 1457] i = 0 sock = -1
[2011-05-20 19:54:20] *ERROR* SOCKET WRITE TIMEOUT In [[redacted]/source/shared_lib/sources/platform/posix/socket.cpp::isWritable Line: 1457] i = 0 sock = -1
[2011-05-20 19:54:20] *ERROR* In [[redacted]/source/glest_game/network/connection_slot.cpp::update Line: 780] Error [In [[redacted]/source/shared_lib/sources/platform/sdl/thread.cpp::p Line: 114] mutex == NULL refCount = 0 owner [[redacted]/source/shared_lib/sources/platform/posix/socket.cpp_841]]
The first two lines are, to my understanding, completely normal, but the last one is not and also displayed on-screen in-game.
I then restarted my game and hosted again and he reconnected to the lobby, and I asked him to disconnect once more. He did and it happened again - so it seems reproducible, at least with him.