Cleanup transformers3 mess

Summary:
transformers (as imported internally) has a convoluted and bloody history.

the current state is that "transformers3" exists alongside "transformers", and makes things messy for upgrades and rollouts, especially considering the hacks applied to "transformers3" historically.

this diff attempts to get closer to a cleaner state, by deleting "transformers3" after existing usage was migrated to "transformers" in the previous diff

Reviewed By: lisroach, diliop

Differential Revision: D68842833

fbshipit-source-id: 13b80b92ee1005f26e6a60907566bd5cc6167a86

Author: itamaro

mmf/modules/vit.py

@@ -8,20 +8,12 @@
 from omegaconf import OmegaConf
 from packaging import version
 from torch import nn
-
-try:
-    from transformers3 import __version__ as transformers_version
-    from transformers3.modeling_bert import BertSelfAttention
-except ImportError:
-    from transformers import __version__ as transformers_version
-    from transformers.modeling_bert import BertSelfAttention
+from transformers import __version__ as transformers_version
+from transformers.modeling_bert import BertSelfAttention
 
 
 if version.parse(transformers_version) >= version.parse("4.5.0"):
-    try:
-        import transformers3.models.vit.modeling_vit as vit
-    except ImportError:
-        import transformers.models.vit.modeling_vit as vit
+    import transformers.models.vit.modeling_vit as vit
 
     has_VIT = True
 else:

mmf/utils/patch.py

@@ -29,10 +29,7 @@ def patch_transformers(log_incompatible=False):
     to look for local folder at the last in path resolver. This is
     reverted back to original behavior at the end of the function.
     """
-    try:
-        import transformers3 as transformers
-    except ImportError:
-        import transformers
+    import transformers
 
     # pl uses importlib to find_transformers spec throwing if None
     # this prevents mmf/__init__() from raising and value error

tests/modules/test_vit.py

@@ -12,10 +12,7 @@
 @skip_if_old_transformers(min_version="4.5.0")
 class TestViT(unittest.TestCase):
     def setUp(self):
-        try:
-            import transformers3.models.vit.modeling_vit as vit
-        except ImportError:
-            import transformers.models.vit.modeling_vit as vit
+        import transformers.models.vit.modeling_vit as vit
 
         setup_proxy()
         config = {