Removes the copied lockfile when the install fails

Author: Maël Nison

packages/create-react-app/createReactApp.js

@@ -429,7 +429,7 @@ function run(
       console.log();
 
       // On 'exit' we will delete these files from target directory.
-      const knownGeneratedFiles = ['package.json', 'node_modules'];
+      const knownGeneratedFiles = ['package.json', 'yarn.lock', 'node_modules'];
       const currentFiles = fs.readdirSync(path.join(root));
       currentFiles.forEach(file => {
         knownGeneratedFiles.forEach(fileToMatch => {