anchor.diff:  
     docker = buildFromGitHub {
       version = 2;
  -    rev = "550b06ab6a9e9e0200b9b5d2f5cb5b7b7b4bb16a";
  +    rev = "fd3aef5ec222e87af34df42d9fcad8e427880760";
       owner = "docker";
       repo = "docker";
  -    sha256 = "18j15h85cbr9d44vqfb1nq9kdm26d31m8abzp6iwax5fi4v8vlfs";
  +    sha256 = "1zbr9823ibz50w05z3gym4kr87kj5bq11nx7p3mvxgm6ajcxkz1r";
       meta.useUnstable = true;
  -    date = "2017-03-20";
  +    date = "2017-03-21";
       propagatedBuildInputs = [
         distribution_for_docker
         errors
  
positive.code:       swift
        sys
        tb
        testify
      ];
      meta.useUnstable = true;
      date = "2017-03-19";
    };
  
negative.code: 
    utp = buildFromGitHub {
      version = 2;
      rev = "05059433a8ebe25962a6a4f9c4b495f71775f78c";
      owner  = "anacrolix";
      repo   = "utp";
      sha256 = "1c9aadpi20ajcf99dk6hnpycc7wlif5sqqbsp41jb4693srcaywf";
      date = "2017-03-21";
      propagatedBuildInputs = [
        envpprof
        missinggo
  