Fix casting queryset to list before finished querying

Review Request #96 — Created June 18, 2025 and updated — Latest diff uploaded

Information

Review Board
ab459d0...

Reviewers

A recent merge introduced a bug where the `FileDiff` queryset in
`get_diff_files` was cast to a list before excluding the filediff
ancestors, which is an operation that expects a queryset. This has been
fixed.