title: Dockerfile COPY instruction failing?
body: <p>All, i'm trying to persistently copy files from my host to an image so those files are available with every container launched based on that image. Running on debian wheezy 64bit as virtualbox guest.</p>
  
  <p>the Dockerfile is fairly simple (installing octave image):</p>
  
  <pre><code>FROM debian:jessie 
  MAINTAINER GG_Python &lt;[redacted]@gmail.com&gt;
  RUN apt-get update 
  RUN apt-get update
  RUN apt-get install -y octave octave-image octave-missing-functions octave-nan octave-statistics
  
  RUN mkdir /octave
  RUN mkdir /octave/libs
  RUN mkdir /octave/libs/jsonlab
  COPY ~/octave/jsonlab/loadjson.m /octave/libs/jsonlab/.
  </code></pre>
  
  <p>I'm getting the following trace after issuing a build command: <code>docker build -t octave .</code></p>
  
  <pre><code>Sending build context to Docker daemon 423.9 kB
  Sending build context to Docker daemon 
  Step 0 : FROM debian:jessie
   ---&gt; 58052b122b60
  Step 1 : MAINTAINER GG_Python &lt;[..]@gmail.com&gt;
   ---&gt; Using cache
   ---&gt; 90d2dd2f7ee8
  Step 2 : RUN apt-get update
   ---&gt; Using cache
   ---&gt; 4c72c25cd829
  Step 3 : RUN apt-get update
   ---&gt; Using cache
   ---&gt; b52f0bcb9f86
  Step 4 : RUN apt-get install -y octave octave-image octave-missing-functions octave-nan octave-statistics
   ---&gt; Using cache
   ---&gt; f0637ab96d5e
  Step 5 : RUN mkdir /octave
   ---&gt; Using cache
   ---&gt; a2d278b2819b
  Step 6 : RUN mkdir /octave/libs
   ---&gt; Using cache
   ---&gt; 65efbbe01c99
  Step 7 : RUN mkdir /octave/libs/jsonlab
   ---&gt; Using cache
   ---&gt; e41b80901266
  Step 8 : COPY ~/octave/jsonlab/loadjson.m /octave/libs/jsonlab/.
  INFO[0000] ~/octave/jsonlab/loadjson.m: no such file or directory 
  </code></pre>
  
  <p>Docker absolutely refuses to copy this file from the host into the image. Needless to say a the file loadjson.m is there (cat displays), all my attempts to change the path (relative, absolute, etc.) failed. Any advice why this simple task is problematic?</p>