Fix bugs in hdfs download (#27344)

* set default value to strategy in distributed_optimizer test=develop

python/paddle/distributed/fleet/utils/fs.py

@@ -749,9 +749,6 @@ class HDFSClient(FS):
                 client = HDFSClient(hadoop_home, configs)
                 client.download("hdfs:/test_hdfs_client", "./")
         """
-        if self.is_exist(local_path):
-            raise FSFileExistsError("{} exists".format(local_path))
-
         if not self.is_exist(fs_path):
             raise FSFileNotExistsError("{} not exits".format(fs_path))
 

python/paddle/fluid/tests/unittests/hdfs_test_utils.py

@@ -157,13 +157,6 @@ class FSTestBase(unittest.TestCase):
 
         assert fs.need_upload_download()
 
-        fs.download(src_file, dst_file)
-        try:
-            fs.download(src_file, dst_file)
-            self.assertFalse(True)
-        except FSFileExistsError as e:
-            pass
-
         self.assertTrue(fs.is_exist(dst_file))
         fs.delete(dst_file)
         fs.delete(src_file)