sftpdrive: Files are erased when renaming them on the server!

When I use Explorer to rename a file located on the server (using context menu or F2), the contents of the file disappear! The length simply changes to zero. Logging in to the server confirms that the file is actually empty, it is not just a reporting problem.

This happens almost every time I try.

sftpdrive version = 1.7.9
local system = Win XP SP3
remote system = IRIX64
Remote protocol version 2.0, remote software version OpenSSH_3.7.1p2
(same thing happens on another IRIX64 machine running protocol version 1.99, software version OpenSSH_3.4p1)