apollo-tooling: Duplicate fields are generated into Fragment interface

I’m using version 0.10.9 and ran into the problem that some properties are generated more than one time into a Fragment interface.

I’ve assembled a very trivial example for this. Schema: zoo.graphql

interface Feedable {
    _id: ID!,
    kind: String!
    feedWith: String!
}


interface Reptile {
    scaleSkin: String!
}

type Crocodile implements Feedable, Reptile {
    _id: ID!,
    kind: String!
    feedWith: String!
    scaleSkin: String!

    victims: Int!
}

type Iguana implements Feedable, Reptile {
    _id: ID!,
    kind: String!
    feedWith: String!
    scaleSkin: String!

    age: Int!
}

root.graphql

type Query {
    getZoo: [Feedable!]!
}

schema {
    query: Query
}

And now I setup a very simple query with some fragments: zooQuery.graphql

query getZoo {
    getZoo {
        ...FeedableFragment
    }
}

FeedableFragment

fragment FeedableFragment on Feedable {
    _id
    kind,
    feedWith

    ... on Reptile {
        scaleSkin
    }

    ... on Crocodile {
        victims
    }

    ... on Iguana {
        age
    }
}

And now I check the generated interfaces and I have this:

export interface FeedableFragment {
  _id: string;
  kind: string;
  feedWith: string;
  _id: string;
  kind: string;
  feedWith: string;
  scaleSkin: string;
  victims: number;
  _id: string;
  kind: string;
  feedWith: string;
  scaleSkin: string;
  age: number;
}

As you can see, the _id, kind, feedWith fields are repeated three times, instead of one. What’s more, I think that the scaleSkin and age properties should be optional properties.