fixes a bug in arctool, =achris

diff --git a/src/executables/ArcTool.php b/src/executables/ArcTool.php
index 8225a6cfb..44375e0ab 100755
--- a/src/executables/ArcTool.php
+++ b/src/executables/ArcTool.php
@@ -540,7 +540,7 @@ class ArcTool implements CrawlConstants
         }
         $shards = glob($path."/posting_doc_shards/index*");
         if (is_array($shards)) {
-            $dbms_manager = C\NS_DATASOURCES . C\DBMS . "Manager";
+            $dbms_manager = C\NS_DATASOURCES . ucfirst(C\DBMS) . "Manager";
             $db = new $dbms_manager();
             if ($max_tier == -1 && $start_shard == 0) {
                 $db->unlinkRecursive($path."/dictionary", false);