We ignore EPIPE and ECONNRESET when handling requests in thinlinc.httpserver. HTTPSRequestHandler as a browser might decide do abandon a connection and just close it. We don't want nasty log messages for this common scenario, hence why we just silently drop things.
However we don't actually make sure it's just for that scenario. So we end up ignoring EPIPE and ECONNRESET from every possible source. A handler might be making other connections that we want to see when they fail.
This has been observed for the VNC socket in tlwebaccess on bug 7552 where we got nothing in the logs despite socket problems.
To fix this we can either make sure we somehow only trigger on writes to the browser. Or we can consider even that a bug and fix up all calls that send things to the browser to handle this scenario.