Unstable state before starting fix of failure to release leaf-to-root parent chain. Much temporary debugging code present.
Fix failure to release leaf-to-root parent chain, albeit with release not occurring in optimal order. Still unstable due to much temporary debugging code present.
Unstable. Fix failure of last() to establish leaf-to-root child->parent chain. Fixes failure in btree_unit_test insert test, but causes new failures in cache tests. Also added code to maintain a minimum max_cache_size, and that may not be working correctly yet.