Mutation changes not yet committed when remote schema relationship is invoked?

Noticed this on Hasura 1.3.3, minimal example:

- Remote schema `remote`:
```gql
type Details {
an_interesting_detail: String
}

schema {
query: {
interesting_object_details(interesting_object_id: uuid!): Details
}
}
```
- Table exposed via Hasura `interesting_objects`:
```sql
CREATE TABLE interesting_objects (
id uuid NOT NULL PRIMARY KEY,
some_field text
);
```
- Remote schema relationship attaching `remote.interesting_object_details` to `interesting_objects.details` with the `id` mapped as parameter.

So now I send this mutation:

```gql
mutation MyMutation {
update_interesting_objects_by_pk(
pk_columns: {
id: "abc123..."
}
_set: {
some_field: "some value"
},
) {
id
some_value
details {
an_interesting_detail
}
}
}
```

The resolver in the remote schema reads from the same DB as Hasura, but it looks like it's getting an older version of the `interesting_object` without the updated value for `some_field`. I set this up locally and also added some delay in the resolver so I think it's because at the time when the remote schema is invoked the mutation transaction hasn't yet been committed. Is this expected behavior?

PS: I know there are other ways to achieve something similar using functions in Postgres, unfortunately in this case I really do need to run some custom code to generate `an_interesting_detail`.

Start with the minimal mutation and remote-schema relationship described in the issue, using the delayed resolver against the same database. Trace whether the mutation is committed before the relationship is resolved; done means the expected transaction behavior is established and the observed stale read is explained or addressed.

Written by the indexing model from the issue text.