code: function parent(dependent) {
      var node = dependent
        , result = [];
  
      while (node.parent) {
        if (!available(node.parent)) break;
  
        result.push(node.parent);
        node = node.parent;
      }
  
      return result;
    }
docs: Find suitable parent nodes which can hold this module without creating
  a possible conflict because there two different versions of the module in
  the dependency tree.
  
  @param {Object} dependent A dependent of a module.
  @returns {Array} parents.
  @api private