Fix simplify for simple domains ['AND'], ['OR']

issue3955
review7321002

src/common.js

@@ -1447,6 +1447,9 @@
                 return domain;
             } else if (~['OR', 'AND'].indexOf(domain)) {
                 return domain;
+            } else if ((domain instanceof Array) && (domain.length == 1) &&
+                    (~['OR', 'AND'].indexOf(domain[0]))) {
+                return [];
             } else if ((domain instanceof Array) && (domain.length == 1) &&
                     (!this.is_leaf(domain[0]))) {
                 return this.simplify(domain[0]);

tests/sao.js

@@ -1710,7 +1710,9 @@
         [['OR', [['x', '=', 3]], [['y', '=', 5]]],
             ['OR', [['x', '=', 3]], [['y', '=', 5]]]],
         [['OR', ['x', '=', 3], ['AND', ['y', '=', 5]]],
-            ['OR', ['x', '=', 3], [['y', '=', 5]]]]
+            ['OR', ['x', '=', 3], [['y', '=', 5]]]],
+        [['AND'], []],
+        [['OR'], []]
         ].forEach(function(test) {
             var domain = test[0];
             var result = test[1];