add backward compatibility support for loading mcore 0.15 checkpoints (NVIDIA#2648)

Signed-off-by: dimapihtar <[email protected]>

Author: dimapihtar

megatron/core/dist_checkpointing/strategies/torch.py

@@ -83,6 +83,13 @@
 _metadata_fn: str = ".metadata"
 
 
+# dummy class needed to load mcore v0.15 checkpoints with optim. states
+class MCoreMetadata:
+    """ """
+
+    pass
+
+
 # dummy class needed to load old checkpoint weights
 class MCoreSavePlan:
     """ """