The very first sample code on the site seems to contain an error: https://ftputil.sschwarzer.net/trac/wiki/Documentation#introduction
with ftp_host.open("index.html", "rb") as source: with ftp_host.open("newdir/index.html", "wb") as target: ftp_host.copyfileobj(source, target) # similar to shutil.copyfileobj
Unless I'm mistaken and my working code is doing something it should not, that should be "with open( ... as source", as a local file, and with "ftp_host.open( ... as target" for the remove file. That is, you're opening the local file as a regular Python file object, not as an ftputil remote object.
It should be possible to copy a remote file to another remote location, as in the example code. Remote files support reading and writing. So I think the code is intentional as it is.
When you say
Unless I'm mistaken and my working code is doing something it should not,
what did you try and in which way did it fail?
My apologies -- somehow I missed the remote file in the comments. Please allow me to hang my head in shame and slink out, while offering thanks for your time and intelligence.
Now, now, it's fine. We all make mistakes. :-)
I do appreciate that you entered a ticket about a documentation bug! Not many people do this. Of course it's possible that a bug isn't really a bug, but naturally you don't know this in advance. So relax and keep entering such tickets. :-)
Closing this as "invalid" because it's not actually a mistake.