title: Docker trouble with too many link
body: <p>During a docker build, i have this error :</p>
  
  <pre><code>Step 1 : FROM million12/nginx-php:latest
   ---&gt; 09c053597dda
  Step 2 : COPY etc/docker-jenkins/default.conf /etc/nginx/hosts.d/default.conf
   ---&gt; Using cache
   ---&gt; 26a29dd01af3
  Step 3 : COPY app /data/www/app
  INFO[0012] link /var/lib/docker/overlay/99380f87e1572466529c4f668b5e79fe711496e9
  85d313cc0d2f45bfdbdb3969/root/var/lib/yum/yumdb/p/939d2078d64d51ff7ad16150745e94
  a26085bc93-php70-php-opcache-7.0.11-1.el7.remi-x86_64/checksum_type /var/lib/doc
  ker/overlay/9ac18f869f20ba8ba29d2a16f00f2ce6ff1c6d0d1a40192a0efb8933c8ad1c45/tmp
  root958106287/var/lib/yum/yumdb/p/939d2078d64d51ff7ad16150745e94a26085bc93-php70
  -php-opcache-7.0.11-1.el7.remi-x86_64/checksum_type: too many links
  </code></pre>
  
  <p>Someone has an idea to fix this ? Inside the app directory there are not many file or directory and not that long.
  I'm on a ext4 fs on a ubuntu 16.04
  Thank you :)</p>