bug#69930: 29.1; onedrive

[Eli Zaretskii <eliz@gnu.org>]

> From: Stephen Vavasis <vavasis@uwaterloo.ca>
> Date: Thu, 21 Mar 2024 12:45:46 +0000
> 
> Emacs does not work properly with the version-history feature of
> Microsoft's OneDrive cloud file system.  The situation arises for a file
> on the C: drive of my Windows machine that sits inside the OneDrive
> cloud-sync'd folder.  When I edit a file like this on my Windows machine
> with emacs, the OneDrive version-history shows only the latest version.
> It seems that the Emacs save-button CTRL-X CTRL-S causes OneDrive to
> discard older versions.  Older versions of the file can still be found
> in the Recycled folder in the cloud.  This is not an ideal place for
> them because Recycled is not easily searched, file names can collide,
> and Recycled is periodically purged.

Does this happen in "emacs -Q"?  If this doesn't happen in "emacs -Q",
you should look for some customization of yours that causes this; in
particular, Emacs by default never writes old versions of files to the
Recycled directory.

If "emacs -Q" also shows this behavior, my suggestion is to try
setting the option backup-by-copying to a non-nil value.