pollInterval is ignored when changing the variables, if both variables and pollInterval are reactive

[rokiyama]

Describe the bug
pollInterval is ignored when changing the variables, if both variables and pollInterval are reactive.

Queries are executed without any waiting time.

To Reproduce
repo: https://github.com/rokiyama/example-vue-apollo-polling/tree/da09dec565df30c042beafa4374e95af691e6cd0

1. Run the repo, open browser
2. change the field name
3. the queries are executed as fast as possible

Expected behavior
Queries are executed with pollInterval value

Versions
vue: 2.6.11
vue-apollo: 3.0.2
apollo-client: 2.6.8

Additional context

[rokiyama]

Workaround: Stop using reactive pollInterval option, call startPolling in result function

The code below solved the problem. Also I had to call startPolling when interval changed, if I set 0 to initial value of pollInterval. (Without this, startPolling will never be executed.)

  apollo: {
    hello: {
      query: gql`
        query hello($name: String) {
          hello(name: $name)
        }
      `,
      variables() {
        return {
          name: this.name
        };
      },
      result(res) {
        if (this.pollInterval > 0) {
          this.$apollo.queries.hello.startPolling(this.pollInterval);
        } else {
          this.$apollo.queries.hello.stopPolling();
        }
      }
    }
  },
  data() {
    return {
      name: "Takashi",
      pollInterval: 0
    };
  },
  computed: {
    pollIntervalInput: {
      get() {
        return this.pollInterval;
      },
      set(newValue) {
        if (newValue > 0) {
          this.$apollo.queries.hello.startPolling(newValue);
        }
        this.pollInterval = newValue;
      }
    }
  }

repo: https://github.com/rokiyama/example-vue-apollo-polling/tree/386e831d6d61bf19879c398be5df8ee217e2dbae

Making pollInterval reactive causes problem?