Move the insert-time check from before_insert to validate. before_insert
runs before set_new_name, so the validation message rendered the
warehouse name as None. validate runs after naming and only applies to
new documents via is_new().
Resolve inheritance through the parent's lft/rgt bounds instead of the
request-cached warehouse account map. The cached map can be stale within
a request (a parent created moments earlier is missing from it), which
made get_warehouse_account trigger a full nested-set rebuild_tree and
could falsely reject a child whose parent carries a valid account.
rebuild_tree enables auto_commit_on_many_writes, which must not run
inside a document insert.
5e3d0947c8