net.server_epoll: Don't immediately destroy upon getting closed on read

Instead try to write any remaining buffered data. If the write attempt
also fails with "closed" then there's nothing we can do and the socket
is gone.

This reverts what appears to be a mistakenly included part of c8aa66595072

Thanks jonas’ for noticing

net/server_epoll.lua

@@ -460,7 +460,7 @@ function interface:onreadable()
 				self:debug("Read error, closing (%s)", err);
 			end
 			self:on("disconnect", err);
-			self:destroy()
+			self:close();
 			return;
 		end
 	end