Handle missing space marker in unified diff during header fixup

* vc/diff-mode.el (diff-fixup-modifs): Handle empty line in
context of unified diff.

1 files changed, 3 insertions, 0 deletions

diff --git a/lisp/vc/diff-mode.el b/lisp/vc/diff-mode.el
index 4908c5f4961..d4e973956c8 100644
--- a/lisp/vc/diff-mode.el
+++ b/lisp/vc/diff-mode.el
@@ -1220,6 +1220,9 @@ else cover the whole buffer."
                 (?- (cl-incf minus))
                 (?! (cl-incf bang))
                 ((or ?\\ ?#) nil)
+                (?\n (if diff-valid-unified-empty-line
+                         (cl-incf space)
+                       (setq space 0 plus 0 minus 0 bang 0)))
                 (_  (setq space 0 plus 0 minus 0 bang 0)))
             (cond
              ((looking-at diff-hunk-header-re-unified)