update test_cat_file_exist test case
update test_cat_file_exist test case

lylei/dfs,linyvxiang/dfs,linyvxiang/dfs,bluebore/bfs,bluebore/dfs,yvxiang/dfs,baidu/bfs,yvxiang/coverage_for_bfs,yvxiang/dfs,baidu/bfs,myawan/bfs-1,yvxiang/coverage_for_bfs,yvxiang/dfs,baidu/bfs,lylei/dfs,yvxiang/coverage_for_bfs,lylei/dfs,myawan/bfs-1,lylei/dfs,bluebore/dfs,bluebore/dfs,myawan/bfs-1,myawan/bfs-1,linyvxiang/dfs,baidu/bfs,yvxiang/coverage_for_bfs,bluebore/bfs,bluebore/bfs,yvxiang/dfs