[Zope] problem saving file twice using ange-ftp

[John Hunter]

I am using ange-ftp in GNU emacs to edit my Zope ZWiki pages.  This
works fine, but when I try and save a page for a second time, I get
the error

Opening output file: FTP Error: "426 Error creating file.", /myuser@nitace.bsd.uchicago.edu 8021:/Wikis/April/FrontPage

If I kill the buffer and then reenter it again, I am allowed to modify
and save it only one time.

Any suggestions about what is going wrong and how to fix it?

Thanks,
John Hunter

Zope 2.3.0
GNU emacs 20.7.1
python 1.5.2