disable new checkpoint by default temporarily (#3943)

* disable new checkpoint by default temporarily
Signed-off-by: Ndaquexian <daquexian566@gmail.com>

* disable test
Signed-off-by: Ndaquexian <daquexian566@gmail.com>
Former-commit-id: c4bbf8c0

oneflow/core/job/job_set.proto

@@ -11,7 +11,7 @@ message IOConf {
   optional bool save_downloaded_file_to_local_fs = 3 [default = false];
   optional uint64 persistence_buf_byte = 4;
   optional bool enable_model_io_v2 = 5 [default = false];
-  optional bool enable_legacy_model_io = 6 [default = false];
+  optional bool enable_legacy_model_io = 6 [default = true];
 }
 
 message ProfilerConf {

oneflow/python/test/ops/test_checkpoint.py

@@ -333,6 +333,7 @@ def _TestAssignmentBetweenMemory(test_case, dtype):
     test_case.assertTrue(np.allclose(flow_res, np_res))
 
 
+@unittest.skip("new checkpoint is disabled temporarily")
 class TestCheckpoint(flow.unittest.TestCase):
     @flow.unittest.skip_unless_1n4d()
     @unittest.skipIf(