title: Dockerfile image build: "RUN wget" inside the Dockerfile results in partial file download, but the build completes with no errors
body: <p>As stated in the title.  Also, same result with curl, also same results regardless of if using the plain RUN versus EXEC mode of RUN with the wget and its args all inside [ ]</p>
  
  <p>The container builds with no errors and when I run it via hijack of the entrypoint with bash I see only a few hundred bytes of the file was actually downloaded, also then from inside the running container I can then wget the complete file and run it.</p>
  
  <p>Did a lot of googling and dont see anyone else with this.<br>
  ???</p>
  
  <pre><code>FROM ubuntu:18.04
  
  RUN echo "APT::Get::Assume-Yes \"true\";" &gt; /etc/apt/apt.conf.d/90assumeyes
  
  RUN apt-get update \
      &amp;&amp; apt-get install \
          ca-certificates \
          jq \
          git \
          curl\
          m4 \
          make \
          patch \
          libev-dev \
          libgmp-dev \
          libhidapi-dev \
          bubblewrap \
          zip \
          unzip \
          g++ \
          pkg-config
  
  WORKDIR /azp
  
  ENV DEBIAN_FRONTEND=noninteractive
  
  RUN ["curl", "-s", "-o", "/usr/local/bin/opam", "https://github.com/ocaml/opam/releases/download/2.0.6/opam-2.0.6-x86_64-linux"]
  
  RUN chmod a+x /usr/local/bin/opam
  
  ENTRYPOINT ["bash"]
  </code></pre>