bug#29956: 26.0.90; `d' in *VC-history*: Wrong type argument: sequencep, 47

[Stefan Monnier <monnier@iro.umontreal.ca>]

Package: Emacs
Version: 26.0.90


    % src/emacs -Q lisp/emacs-lisp/pcase.el
    ...Select the first (def-edebug-spec ...)
    C-x v h
    In the *VC-history* buffer, hit `d'

This gives me `Wrong type argument: sequencep, 47'
[ Which file you use, and which region of the file you select doesn't
  really matter.  ]

The patch below fixes it for me.

Is it OK to install it into emacs-26, or should I keep it on `master`?

FWIW, it's not a new bug in Emacs-26 and it's not terribly urgent to fix
it, e.g. because you can use `D' which does work (tho it doesn't do
quite the same), so I'm fine with either choice.


        Stefan


diff --git a/lisp/vc/vc.el b/lisp/vc/vc.el
index 7c502f88df..0a87e70017 100644
--- a/lisp/vc/vc.el
+++ b/lisp/vc/vc.el
@@ -2426,9 +2426,11 @@ vc-region-history
       (setq-local vc-log-view-type 'long))
     (vc-call region-history file buf lfrom lto)
     (with-current-buffer buf
+      (setq default-directory (file-name-directory file))
       (vc-call-backend backend 'region-history-mode)
       (set (make-local-variable 'log-view-vc-backend) backend)
-      (set (make-local-variable 'log-view-vc-fileset) file)
+      (set (make-local-variable 'log-view-vc-fileset)
+           (list (file-relative-name file)))
       (set (make-local-variable 'revert-buffer-function)
 	   (lambda (_ignore-auto _noconfirm)
              (with-current-buffer buf