title: Docker `COPY` file not working
body: <p>I have a relatively simple dockerfile</p>
  
  <pre><code>FROM python:3.6.5-alpine
  
  COPY somebinary /usr/local/bin/
  
  COPY install.sh /install.sh
  RUN /install.sh
  </code></pre>
  
  <p>The binary gets copied across just fine (when I run the container to check) but the script doesn't seem to get copied across so that when I try to run it I get:</p>
  
  <pre><code>Step 4/5 : COPY install.sh /install.sh
   ---&gt; 38ecc6dbad13
  Step 5/5 : RUN /install.sh
   ---&gt; Running in 0b06962d6e1b
  /bin/sh: /install.sh: not found
  The command '/bin/sh -c /install.sh' returned a non-zero code: 127
  </code></pre>
  
  <p>The same happens with any other test files I make, they aren't available when the image is run. Other people have had success running the exact same script so I suspect it could be to do with the fact that I'm running docker through Git Bash on Windows? Could it be a permissions thing?</p>
  
  <p>e: I went and tried running through powershell and got the same error, so perhaps git bash is a red herring</p>