Custom scalars don't seem to work for schema delegation/remote schemas

[schickling]

Proxying fields with custom scalar values (like DateTime) doesn't seem to work right now using remote schemas/schema delegation.

Here is an example using the GraphQL binding for Github: https://graphqlbin.com/rozCD
Code: https://github.com/graphcool/github-graphql-binding

Observation:

Currently the application schema re-exposes the createdAt field using the "original" DateTime! type which leads to the error above. However, when using String! as the field type for createdAt it doesn't throw an error.

  # doesn't work
  createdAt: DateTime!
  # works
  createdAt: String!

[stubailo]

I think this is a duplicate of #501, thanks for reporting!

[freiksenet]

This looks like an issue with graphql-import. I can use custom scalars fine by using Github.schema directly.