More not-state-changing vc commands can be used from non-file buffers

* lisp/vc/vc.el (vc-deduce-fileset): Instead of checking for
log-view-mode, check for '(not buffer-file-name)' before trying to
get the backend for default-directory.  Remove the branch that
checks for '(not buffer-file-name)' and signals the error because
vc-responsible-backend used in previous condition already signals
its error.  (Bug#41974)

1 files changed, 1 insertions, 3 deletions

diff --git a/lisp/vc/vc.el b/lisp/vc/vc.el
index 9b12d449785..65775f8e46e 100644
--- a/lisp/vc/vc.el
+++ b/lisp/vc/vc.el
@@ -1074,11 +1074,9 @@ BEWARE: this function may change the current buffer."
       (progn                  ;FIXME: Why not `with-current-buffer'? --Stef.
         (set-buffer vc-parent-buffer)
         (vc-deduce-fileset not-state-changing allow-unregistered state-model-only-files)))
-     ((and (derived-mode-p 'log-view-mode)
+     ((and (not buffer-file-name)
            (setq backend (vc-responsible-backend default-directory)))
       (list backend nil))
-     ((not buffer-file-name)
-       (error "Buffer %s is not associated with a file" (buffer-name)))
      ((and allow-unregistered (not (vc-registered buffer-file-name)))
       (if state-model-only-files
           (list (vc-backend-for-registration (buffer-file-name))