Why does a RegExp with global flag give wrong results?

What is the problem with this regular expression when I use the global flag and the case insensitive flag? Query is a user generated input. The result should be [true, true].

var query = 'Foo B';
var re = new RegExp(query, 'gi');
var result = [];
result.push(re.test('Foo Bar'));
result.push(re.test('Foo Bar'));
// result will be [true, false]

var reg = /^a$/g;
for(i = 0; i++ < 10;)
   console.log(reg.test("a"));