1 files changed, 5 insertions, 2 deletions

diff --git a/lisp/vc/vc.el b/lisp/vc/vc.el
index c640ba0420e..af7339f34b3 100644
--- a/lisp/vc/vc.el
+++ b/lisp/vc/vc.el
@@ -957,7 +957,7 @@ 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
@@ -967,7 +967,10 @@ 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,