As part of the resolution of bug 300426, the DB and OracleDB licenses were merged into Sleepycat. In the main tree the LICENSE variable was changed in the sys-libs/db ebuilds, but prefix never picked up this change and still refers to DB and OracleDB, which no longer exist in the licenses directory.
the licences were all updated to Sleepycat and/or AGPL-3, thanks!