title: Dockerfile 'RUN git clone' removes intermediate container
body: <p>I using Boot2Docker on Windows 7 to build my developement environment with a Dockerfile. When i run <code>docker build -t myimage dir/of/docker/file</code>, then everything works fine until this line:</p>
  
  <pre><code>RUN git clone --verbose https://github.com/zsh-users/antigen ~/.antigen/antigen
  </code></pre>
  
  <p>The output of this line is:</p>
  
  <pre><code>Step 12 : RUN git clone --verbose https://github.com/zsh-users/antigen ~/.antigen/antigen
  ---&gt; Running in 26cba91e912a
  Cloning into '/root/.antigen/antigen'...
  POST git-upload-pack (302 bytes)
  ---&gt; e0012659884b
  Removing intermediate container 26cba91e912a
  Successfully built e0012659884b
  </code></pre>
  
  <p>The clone (of a public repository) is droped, the ~/.antigen/antigen isn't exists in the container.
  The "Cloning into..." is red, so i think there is something wrong with the command. But if i'm running it in the container's shell (opened by <code>docker run -it myimage</code>) it clones it.</p>
  
  <p>Am i doing something wrong, or may i do some setup to use <code>git clone</code> in dockerfile? Here's the full content of it:</p>
  
  <pre><code>FROM debian:testing
  MAINTAINER BimbaLaszlo
  
  RUN apt-get update
  
  RUN apt-get install -y curl
  
  RUN apt-get install -y gcc g++ make
  RUN apt-get install -y ctags
  RUN apt-get install -y git
  
  RUN apt-get install -y python python-pip python3 python3-pip
  
  RUN apt-get install -y ruby ruby-dev
  RUN gem install ripper-tags gem-ripper-tags
  RUN gem install pry byebug
  
  RUN apt-get install -y zsh
  RUN git clone --progress --verbose https://github.com/zsh-users/antigen ~/.antigen/antigen
  </code></pre>