Merge branch 'maint'

* maint:
  diff-patch: Avoid emitting double-slashes in textual patch.
  Reword git-am 3-way fallback failure message.
  Limit filename for format-patch
  core.legacyheaders: Use the description used in RelNotes-1.5.0
  git-show-ref --verify: Fail if called without a reference

Conflicts:

	builtin-show-ref.c
	diff.c

builtin-show-ref.c

@@ -221,9 +221,11 @@ int cmd_show_ref(int argc, const char **argv, const char *prefix)
 	}
 
 	if (verify) {
-		unsigned char sha1[20];
-
+		if (!pattern)
+			die("--verify requires a reference");
 		while (*pattern) {
+			unsigned char sha1[20];
+
 			if (!prefixcmp(*pattern, "refs/") &&
 			    resolve_ref(*pattern, sha1, 1, NULL)) {
 				if (!quiet)