bug#66211: 30.0.50; C-x v v in vc-diff does not work with lesser versionf of patch

[Eli Zaretskii]

> From: "Alfred M. Szmidt" <ams@gnu.org>
> Date: Tue, 26 Sep 2023 08:17:27 -0400
> 
> 
> The C-x v v command in a *vc-diff* buffer does not work if you have a
> lesser version of patch, e.g., the one on OpenBSD:
> 
> user-error: Patch failed: patch: unknown option -- no-backup-if-mismatch
> usage: patch [-bCcEeflNnRstuv] [-B backup-prefix] [-D symbol] [-d directory]
>              [-F max-fuzz] [-i patchfile] [-o out-file] [-p strip-count]
>              [-r rej-name] [-V t | nil | never] [-x number] [-z backup-ext]
>              [--posix] [origfile [patchfile]]
>        patch <patchfile

I don't understand: does "git apply" invoke Patch?  AFAICT, "C-x v v"
in a *vc-diff* buffer runs "git apply FILE", where FILE is a temporary
patch file created from the diffs to be applied.  What am I missing?