While this should be rather exceptional situation, it is possible for public instance to be temporarily unavailable for second phase of transaction resulting in failure to finish such transaction. Until now this situation have been treated as critical failure and forcing administrator to initiate manual cleanup of content under such failed transaction in order to restore operations. In order to expedit processing in less stable environments, such condition will be now treated as recoverable error - Magnolia will automatically expire locks on such content in configurable time interval (by default within 15 minutes).
To configure such interval to different then default value please set transactionExpireSeconds property of XAReceiveFilter under /server/filters/activation to desired value (default is 900).