This is part of the DB upgrade to version 13.
It seems that at this moment of time, this only upgrades a single tx, 47f663238196a8376dffeb867727b7794f1a86e97d7401dd141ac8c072f91c54. However, if someone is updating the DB at a later stage, this code will handle this gracefully (and there seems indication that more txs of this form will come in the future).
Note that this uses the (erroneously added) indexing of OP_RETURN scripts, which actually will be removed as part of D16941. This way the upgrade is basically instant (instead of requiring a full search through all txs, or requiring the LOKAD ID index to be enabled).