bugfix: make sure we get the hive_meta values from the naked table cache properly

modules/Bio/EnsEMBL/Hive/DBSQL/MetaAdaptor.pm

@@ -51,7 +51,8 @@ sub get_value_by_key {
 
     if( my $collection = Bio::EnsEMBL::Hive::MetaParameters->collection() ) {
 
-        return $collection->find_one_by( 'meta_key', $meta_key );
+        my $hash = $collection->find_one_by( 'meta_key', $meta_key );
+        return $hash && $hash->{'meta_value'};
 
     } else {    # TODO: to be removed when beekeeper.pl/runWorker.pl become collection-aware