Using @refetchable on a fragment of an interface type results in "Internal Error: Unknown type: 'Node'."

https://github.com/rovaughn/relay-bug contains a minimal example demonstrating the behavior.

Start with the linked minimal example in rovaughn/relay-bug and reproduce the failure involving @refetchable on an interface fragment. Trace the relevant Relay processing entry point to determine why the example reports Unknown type: 'Node'; done means the example processes successfully without that internal error.

Written by the indexing model from the issue text.