should watch the full scss dep tree: fix race

We are getting test failures:

1) cli node-sass in.scss should watch the full scss dep tree for a single file:

      Uncaught AssertionError: false == true

      + expected - actual

      -false

      +true

      at Socket.<anonymous> (test/cli.js:317:9)
      at readableAddChunk (_stream_readable.js:146:16)
      at Socket.Readable.push (_stream_readable.js:110:10)
      at Pipe.onread (net.js:523:20)

test/cli.js

@@ -303,7 +303,7 @@ describe('cli', function() {
 
     it('should watch the full scss dep tree for a single file', function(done) {
       var src = fixture('watching/index.scss');
-      var foo = fixture('watching/foo.scss');
+      var foo = fixture('watching/white.scss');
 
       fs.writeFileSync(foo, '');
 

test/fixtures/watching/white.scss

@@ -0,0 +1 @@
+body{background:white}