1 files changed, 7 insertions, 3 deletions

diff --git a/lisp/vc/vc.el b/lisp/vc/vc.el
index ce947d21f95..9b12d449785 100644
--- a/lisp/vc/vc.el
+++ b/lisp/vc/vc.el
@@ -964,7 +964,7 @@ use."
       (throw 'found bk))))
 
 ;;;###autoload
-(defun vc-responsible-backend (file)
+(defun vc-responsible-backend (file &optional no-error)
   "Return the name of a backend system that is responsible for FILE.
 
 If FILE is already registered, return the
@@ -974,7 +974,10 @@ responsible for FILE is returned.
 
 Note that if FILE is a symbolic link, it will not be resolved --
 the responsible backend system for the symbolic link itself will
-be reported."
+be reported.
+
+If NO-ERROR is nil, signal an error that no VC backend is
+responsible for the given file."
   (or (and (not (file-directory-p file)) (vc-backend file))
       (catch 'found
         ;; First try: find a responsible backend.  If this is for registration,
@@ -982,7 +985,8 @@ be reported."
         (dolist (backend vc-handled-backends)
           (and (vc-call-backend backend 'responsible-p file)
                (throw 'found backend))))
-      (error "No VC backend is responsible for %s" file)))
+      (unless no-error
+        (error "No VC backend is responsible for %s" file))))
 
 (defun vc-expand-dirs (file-or-dir-list backend)
   "Expands directories in a file list specification.