Block-scoped variable declarations emitted incorrectly for --target ES6

[plantain-00]

version: typescript@1.8.0-dev.20151019

steps:

a.ts

async function a() {
    try {
        let status = 2;
        status = 3
    }
    catch (e) {

    }
}

run tsc a.ts -t es6 -m commonjs

result: a.js

var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promise, generator) {
    return new Promise(function (resolve, reject) {
        generator = generator.call(thisArg, _arguments);
        function cast(value) { return value instanceof Promise && value.constructor === Promise ? value : new Promise(function (resolve) { resolve(value); }); }
        function onfulfill(value) { try { step("next", value); } catch (e) { reject(e); } }
        function onreject(value) { try { step("throw", value); } catch (e) { reject(e); } }
        function step(verb, value) {
            var result = generator[verb](value);
            result.done ? resolve(result.value) : cast(result.value).then(onfulfill, onreject);
        }
        step("next", void 0);
    });
};
function a() {
    return __awaiter(this, void 0, Promise, function* () {
        try {
            let status = 2;
            status_1 = 3;
        }
        catch (e) {
        }
    });
}

@RyanCavanaugh

[rbuckton]

To clarify, this isn't an issue with async as it repros with out async. The issue is how we emit nested redeclarations for let when using --target es6 with --module. I have a fix inbound, should be available shortly.