Renaming a collection across a database is similar to $out in that it creates a new temporary collection, creates matching indexes on the temporary collection, inserts documents into the temporary collection, and renames the temporary collection over the source. However, unlike $out, renaming across a database marks the insert oplog entries with {fromMigrate: true}. This prevents insert change events from being emitted for the temporary collection. We should stop setting {fromMigrate: true} to bring the $out and renameCollection behaviors into alignment.