syntax: add regression test for recent 'not not x' parser bug

This test exercises a case that would not have been fixed
by the proposed solution (#128), which allowed any number
of not operators to be applied to a primary (such as True)
but did not allow multiple not operators on other expressions
(such as the binary operator 1 >= 1).

Change-Id: Ide956076bb868b834f3613e2ca1203a54610cfae
diff --git a/testdata/ b/testdata/
index 4e6e622..f6adf06 100644
--- a/testdata/
+++ b/testdata/
@@ -6,6 +6,7 @@
 assert.true(not False)
 assert.true(not not True)
+assert.true(not not 1 >= 1)
 # bool conversion