updated for version 7.3.1219
Problem:    No test for using []] inside \%[].
Solution:   Add a test.
diff --git a/src/testdir/test64.ok b/src/testdir/test64.ok
index 7021d18..fa31c8a 100644
--- a/src/testdir/test64.ok
+++ b/src/testdir/test64.ok
@@ -839,6 +839,9 @@
 OK 0 - b\%[[ao]r]
 OK 1 - b\%[[ao]r]
 OK 2 - b\%[[ao]r]
+OK 0 - b\%[[]]r]
+OK 1 - b\%[[]]r]
+OK 2 - b\%[[]]r]
 OK 0 - goo\|go
 OK 1 - goo\|go
 OK 2 - goo\|go