question: private RepositoryEquivalence processMigration ( SubmittedMigration migration , Db db , boolean inverse ) { if ( db . hasMigration ( migration ) ) { ui . message ( "Skipping: already recorded %s -> %s" , migration . fromRevision ( ) , migration . toRevision ( ) ) ; return null ; } Task t = ui . pushTask ( "process_migration" , "Bookkeeping migrated revision %s" , migration ) ; RepositoryEquivalence equivalence = ( inverse ) ? determineEquivalence ( migration . toRevision ( ) , migration . fromRevision ( ) ) : determineEquivalence ( migration . fromRevision ( ) , migration . toRevision ( ) ) ; if ( equivalence != null ) { db . noteEquivalence ( equivalence ) ; ui . message ( "SUCCESS: Equivalence found and recorded: %s" , equivalence ) ; } db . noteMigration ( migration ) ; db . write ( ) ; ui . popTask ( t , "" ) ; return equivalence ; }
target:  Check a submitted migration for equivalence by translating the from-repo to the to-repo, or in the case of an inverse translation, translating the to-repo to the from-repo via the forward-translator.  A representation of that equivalence is returned, if one is found, or null if no equivalence is found.