builtin-for-each-ref.c::copy_name() - do not overstep the buffer.

This was introduced during xmemdupz() conversion.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-for-each-ref.c

@@ -309,7 +309,7 @@ static const char *copy_line(const char *buf)
 static const char *copy_name(const char *buf)
 {
 	const char *cp;
-	for (cp = buf; *cp != '\n'; cp++) {
+	for (cp = buf; *cp && *cp != '\n'; cp++) {
 		if (!strncmp(cp, " <", 2))
 			return xmemdupz(buf, cp - buf);
 	}