Try to fix CI

Author: gaearon

packages/babel-preset-react-app/package.json

@@ -14,7 +14,7 @@
   "dependencies": {
     "@babel/core": "7.0.0-beta.37",
     "@babel/plugin-proposal-class-properties": "7.0.0-beta.37",
-    "@babel/plugin-syntax-dynamic-import": "^7.0.0-beta.37",
+    "@babel/plugin-syntax-dynamic-import": "7.0.0-beta.37",
     "@babel/plugin-transform-classes": "7.0.0-beta.37",
     "@babel/plugin-transform-destructuring": "7.0.0-beta.37",
     "@babel/plugin-transform-react-constant-elements": "7.0.0-beta.37",

packages/react-scripts/package.json

@@ -26,7 +26,7 @@
     "autoprefixer": "7.2.5",
     "babel-core": "7.0.0-bridge.0",
     "babel-eslint": "8.2.1",
-    "babel-jest": "22.0.6",
+    "babel-jest": "22.1.0",
     "babel-loader": "8.0.0-beta.0",
     "babel-preset-react-app": "^3.1.1",
     "case-sensitive-paths-webpack-plugin": "2.1.1",
@@ -45,7 +45,7 @@
     "file-loader": "1.1.6",
     "fs-extra": "5.0.0",
     "html-webpack-plugin": "2.30.1",
-    "jest": "22.0.6",
+    "jest": "22.1.1",
     "object-assign": "4.1.1",
     "postcss-flexbugs-fixes": "3.2.0",
     "postcss-loader": "2.0.10",

packages/react-scripts/scripts/eject.js

@@ -237,21 +237,8 @@ inquirer
     }
 
     if (fs.existsSync(paths.yarnLockFile)) {
-      // TODO: this is disabled for three reasons.
-      //
-      // 1. It produces garbage warnings on Windows on some systems:
-      //    https://github.com/facebookincubator/create-react-app/issues/2030
-      //
-      // 2. For the above reason, it breaks Windows CI:
-      //    https://github.com/facebookincubator/create-react-app/issues/2624
-      //
-      // 3. It is wrong anyway: re-running yarn will respect the lockfile
-      //    rather than package.json we just updated. Instead we should have
-      //    updated the lockfile. So we might as well not do it while it's broken.
-      //    https://github.com/facebookincubator/create-react-app/issues/2627
-      //
-      // console.log(cyan('Running yarn...'));
-      // spawnSync('yarnpkg', [], { stdio: 'inherit' });
+      console.log(cyan('Running yarn...'));
+      spawnSync('yarnpkg', ['--cwd', process.cwd()], { stdio: 'inherit' });
     } else {
       console.log(cyan('Running npm install...'));
       spawnSync('npm', ['install', '--loglevel', 'error'], {