Problem: `ftpcmd` wrapped every command in `ftp.voidcmd()`, which
expects a final 2xx response. `RNFR` returns 350 (intermediate),
so `voidcmd` raised an exception before `RNTO` was ever sent,
causing every rename to fail with '350 Ready for destination name'.
Solution: change `ftpcmd` to accept raw Python lines instead of FTP
command strings, then use `ftp.rename(src, dst)` for the rename case.
`ftplib.rename` handles the 350 intermediate response correctly
internally. All other callers now wrap their FTP commands in
`ftp.voidcmd()` explicitly.
Barrett Ruth
c90c5fcfaa
