Minor comment change.
Release checkpoint lock when waiting for auto-commit transactions to sync, improving concurrency.

Confirmation timeout now represented by an exception.
Merge remote-tracking branch 'remotes/origin/master' into stream
Removed returns from confirm methods.
Eliminate double exception handling.
Ensure auto-reset operations do so even when an exception is thrown.
Discard lingering cursor frames when unreferenced tree is reclaimed.
Merge remote-tracking branch 'remotes/origin/master' into stream