snapshotAt
fun snapshotAt(ref: String, parentDir: File, cache: SnapshotCache, extract: (File) -> String): String
Returns the serialized snapshot for ref, extracting it in a worktree via extract on a cache miss and caching the result by SHA.
Returns the serialized snapshot for ref, extracting it in a worktree via extract on a cache miss and caching the result by SHA.