Do not save sourcemaps

util/prepare.js

@@ -1,14 +1 @@
 require.requireActual('babel/polyfill');
-require.requireActual('source-map-support').install({
-  retrieveSourceMap: function(filename) {
-    if (filename.indexOf('node_modules') === -1) {
-      try {
-        return {
-          map: require.requireActual('fs').readFileSync('/tmp/' + require('crypto').createHash('md5').update(filename).digest('hex') + '.map', 'utf8')
-        };
-      } catch (err) {
-        return undefined;
-      }
-    }
-  }
-});