title: git add . command no response when adding node_modules
body: <p>I have run </p>
  
  <pre><code>git init
  npm install --save-dev webpack
  </code></pre>
  
  <p>Then, there is a package.json and a node_modules directory in the root directory.
  I want to add the node_modules directory into git repo.
  After I run </p>
  
  <pre><code>git add .
  </code></pre>
  
  <p>There is no response any more. And I found the git.exe process occupy more and more memory usage , but there is not any response after several hours.
  What is wrong with it? 
  Is it caused by pretty much files to be added into repo by git?
  How can I debug what happens in detail when that command is executed?
  Everything works fine if I just <code>git add</code> some other files/folder which is not node_modules.
  <a href="https://i.stack.imgur.com/ruiKI.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ruiKI.png" alt="enter image description here"></a></p>