Fix BulkImport concurrent rwalk
diff --git a/src/main/java/org/apache/accumulo/testing/randomwalk/concurrent/BulkImport.java b/src/main/java/org/apache/accumulo/testing/randomwalk/concurrent/BulkImport.java
index 4dd9736..b3ebe27 100644
--- a/src/main/java/org/apache/accumulo/testing/randomwalk/concurrent/BulkImport.java
+++ b/src/main/java/org/apache/accumulo/testing/randomwalk/concurrent/BulkImport.java
@@ -97,7 +97,7 @@
 
     FileSystem fs = FileSystem.get(env.getHadoopConfiguration());
 
-    String bulkDir = "/tmp/concurrent_bulk/b_"
+    String bulkDir = env.getHdfsRoot() + "/tmp/concurrent_bulk/b_"
         + String.format("%016x", rand.nextLong() & 0x7fffffffffffffffl);
 
     fs.mkdirs(new Path(bulkDir));