title: Docker build command fails on COPY
body: <p>Hi I have a docker file which is failing on the <strong>COPY</strong> command. It was running fine initially but then it suddenly crashed during the build process. The Docker file basically sets up the dev environment and authenticate with GCP. </p>
  
  <pre><code>FROM ubuntu:16.04
  
  ## ENV Variables
  ENV PYTHON_VERSION="3.6.5"
  ENV BUCKET_NAME='detection-sandbox'
  ENV DIRECTORY='/usr/local/gcloud'
  
  # Update and Install packages
  RUN apt-get update -y \
   &amp;&amp; apt-get install -y \
   curl \
   wget \
   tar \
   xz-utils \
   bc \
   build-essential \
   cmake \
   curl \
   zlib1g-dev \
   libssl-dev \
   libsqlite3-dev \
   python3-pip \
   python3-setuptools \
   unzip \
   g++ \
   git \
   python-tk
  
   # Install Python 3.6.5
  RUN wget https://www.python.org/ftp/python/${PYTHON_VERSION}/Python-${PYTHON_VERSION}.tar.xz \
      &amp;&amp; tar -xvf Python-${PYTHON_VERSION}.tar.xz \
      &amp;&amp; rm -rf Python-${PYTHON_VERSION}.tar.xz \
      &amp;&amp; cd Python-${PYTHON_VERSION} \
      &amp;&amp; ./configure \
      &amp;&amp; make install \
      &amp;&amp; cd / \
      &amp;&amp; rm -rf Python-${PYTHON_VERSION}
  
  # Install pip
  RUN curl -O https://bootstrap.pypa.io/get-pip.py \
      &amp;&amp; python3 get-pip.py \
      &amp;&amp; rm get-pip.py
  
  # Add SNI support to Python
  RUN pip --no-cache-dir install \
          pyopenssl \
          ndg-httpsclient \
          pyasn1
  
  ## Download and Install Google Cloud SDK
  RUN mkdir -p /usr/local/gcloud \
      &amp;&amp; curl https://sdk.cloud.google.com &gt; install.sh \
      &amp;&amp; bash install.sh --disable-prompts --install-dir=${DIRECTORY}
  
  # Adding the package path to directory
  ENV PATH $PATH:${DIRECTORY}/google-cloud-sdk/bin
  
  # working directory
  WORKDIR /usr/src/app
  
  COPY requirements.txt ./ \
       testproject-264512-9de8b1b35153.json ./
  </code></pre>
  
  <p>It fails at this step : </p>
  
  <pre><code>Step 13/21 : COPY requirements.txt ./      testproject-264512-9de8b1b35153.json ./
  COPY failed: stat /var/lib/docker/tmp/docker-builder942576416/testproject-264512-9de8b1b35153.json: no such file or directory
  </code></pre>
  
  <p>Any leads in this would be helpful. </p>