code: function setVars(origEnv, setVars) {
    var key;
    if (typeof setVars !== 'object')
      return;
    if (Array.isArray(setVars))
      return;
    for (key in setVars) {
      if (has(setVars, key)) {
        if (!has(origEnv, key)) {
          origEnv[key] = [
            !!has(process.env, key),
            process.env[key]
          ];
        }
        process.env[key] = setVars[key];
      }
    }
    return;
  }
docs: add or modify items in env based on key/value pairs in setVars and
  save state information for later
  @arg {Object} origEnv - place to save state of original env
  @arg {Object} setVars - modifications to apply to current env
  @function