Fix missing db servers

git-svn-id: https://redmine.imt-atlantique.fr/svn/xaal/code/Python/branches/0.7@2639 b32b6428-25c9-4566-ad07-03861ab6144f

apps/tools/xaal/tools/querydb.py

@@ -80,6 +80,9 @@ def main():
             eng = Engine()
             eng.start()
             db_servers = isalive.search(eng,'metadatadb.basic')
+            if len(db_servers) == 0:
+                print("No metadb server found")
+                return
             dev = QueryDB(eng,db_servers)
             dev.query(addr)
             print("Time : %0.3f sec" % (time.time() -t0))