Quite often, the file really is already present on the server, although sometimes it isn't yet.
Does anyone know how to avoid this behaviour? Is this a problem with the ssh protocol and is it possible to circumvent this with some clever heuristics? Or perhaps we have configured some settings wrongly? (I set server response timeout to 20-30 secs, execue keep alive via dummy protocol commands every 20 secs)
I have to congratulate prikryl for giving us WinSCP which is such a nice and well designed program that has tremendously boosted our development productivity and removing this little annoyance would seem to be the last step towards development nirvana (we interactively edit files on the server and save every few minutes and this small problem is really killing the workflow speed).
I should also note that this may be happening more often with small files (e.g. <10K in size) (or perhaps just get noticed more often...)
This has happened across all the versions of WinSCP in recent memory, including the latest stable one, I have not yet tried the beta though.
I have not done scientific verification yet, but it also seems to happen on all the different servers we've tried accessing via WinSCP and on all ISP connections (good or bad) that we have used.
Transfer protocol is SFTP, maybe SCP should be default?