Bug: Using a variable in multiple queries only works for first query

I'm using python graphql 2.2.1 with python 3.7. And here is my query:
```gql
query allPhotos($page: Int, $perPage: Int, $sortField: String, $sortOrder: String, $filter: PhotoFilter) {
items: allPhotos(page: $page, perPage: $perPage, sortField: $sortField, sortOrder: $sortOrder, filter: $filter) {
id
photographer_id
event_id
source
thumbnail
created_at
updated_at
__typename
}
total: _allPhotosMeta(page: $page, perPage: $perPage, filter: $filter) {
count
__typename
}

}
```
with the following variable:
```json
{
"filter": {"userId": "1"}
}
```
So here is what happens:
`filter` variable is only populated in `allPhotos` query and `_allPhotosMeta` `filter` variable is `None`. But if I add a new variable like `filter2` equal to `filter` I get the correct result. This only happens in Python. It's ok in NodeJS.