Subject: Re: bug#66212: 30.0.50; C-x v v and vc-diff with fossil-scm

From: Dmitry Gutov <[email-masked]>
Date: Tue, 26 Sep 2023 16:45:22 +0300

On 26/09/2023 15:25, Alfred M. Szmidt wrote:
> When trying to use C-x v v in a vc-diff buffer, and when the version
> control system is Fossil (this is using GNU patch):
> 
> Checking in foo...
> user-error: Patch failed: can't find file to patch at input line 5
> Perhaps you used the wrong -p or --strip option?
> The text leading up to this was:
> --------------------------
> |Index: foo
> |==================================================================
> |--- foo
> |+++ foo
> --------------------------
> File to patch:
> Skip this patch? [y]
> Skipping patch.
> 1 out of 1 hunk ignored
> 
> 
> To reproduce, make a empty Fossil repostiroy, add and commit a file,
> add a line, C-x v =, C-x v v.  vc-fossil has to be installed.

Could you do some more investigation?

Is it just that 'patch' is unable to recognize the format of the diff 
file? Or is it launched from the wrong directory? With wrong arguments?