Avoid a warning about an invalid config option

GraphDatabaseConfiguration.getLocalConfiguration sets the
"gremlin.graph" property to TitanFactory's full package and classname.
MapReduceIndexManagement doesn't need this key, and it leads to a
scary warning when copying the graph's local configuration into a
Hadoop configuration object for use in an index management job.
Removing this key to avoid the warning.

titan-hadoop-parent/titan-hadoop-core/src/main/java/com/thinkaurelius/titan/hadoop/MapReduceIndexManagement.java

@@ -162,7 +162,9 @@ public TitanManagement.IndexJobFuture updateIndex(TitanIndex index, SchemaAction
         titanmrConf.set(TitanHadoopConfiguration.SCAN_JOB_CONFIG_ROOT,
                 GraphDatabaseConfiguration.class.getName() + "#JOB_NS");
         // Copy the StandardTitanGraph configuration under TitanHadoopConfiguration.TITAN_INPUT_CONFIG_KEYS
-        copyInputKeys(hadoopConf, graph.getConfiguration().getLocalConfiguration());
+        org.apache.commons.configuration.Configuration localbc = graph.getConfiguration().getLocalConfiguration();
+        localbc.clearProperty(Graph.GRAPH);
+        copyInputKeys(hadoopConf, localbc);
 
         String jobName = HadoopScanMapper.class.getSimpleName() + "[" + indexJobClass.getSimpleName() + "]";