Compressor not handling combination of conditional and boolean properly

[tonylukasavage]

Node 0.8.17, uglify-js 2.2.5

var u = require('uglify-js');
var ast = u.parse('var a = "string" === "string"');
ast.figure_out_scope();
ast.transform(u.Compressor({
    // should be defaults, but just in case...
    booleans: true,
    conditionals: true,
    comparisons: true
}));
console.log(ast.print_to_string());

I would expect that this would result in the following code:

var a=!0;

It instead generates the following code:

var a=true;

This conversion occurs just fine separately, meaning that if I used var a=true; as my source code, it would compress to var a=!0;. It just seems as though nodes are not being re-evaluated after manipulation in some cases. It's also worth noting that this compression worked as expected in uglify-js v1.