walk around for import check

modeling_jetmoe.py

@@ -9,7 +9,6 @@ from torch import nn
 from torch.nn import CrossEntropyLoss, MSELoss, BCEWithLogitsLoss
 from torch.nn import functional as F
 
-#import megablocks
 from transformers.modeling_outputs import (
     BaseModelOutputWithPast, 
     CausalLMOutputWithPast,
@@ -30,9 +29,14 @@ from transformers.cache_utils import Cache, DynamicCache
 from .configuration_jetmoe import JetMoEConfig
 from . import moe
 
-if is_flash_attn_2_available():
-    from flash_attn import flash_attn_func, flash_attn_varlen_func
-    from flash_attn.bert_padding import index_first_axis, pad_input, unpad_input  # noqa
+try:
+    if is_flash_attn_2_available():
+        from flash_attn import flash_attn_func, flash_attn_varlen_func
+        from flash_attn.bert_padding import index_first_axis, pad_input, unpad_input  # noqa
+except ImportError:
+    # Workaround for https://github.com/huggingface/transformers/issues/28459,
+    # don't move to contextlib.suppress(ImportError)
+    pass
 
 logger = logging.get_logger(__name__)