Move dep checks before fairseq imports in hubconf.py (fixes facebookr…

…esearch#3093) (facebookresearch#3104)

Summary: Pull Request resolved: facebookresearch#3104

Reviewed By: alexeib

Differential Revision: D25786013

Pulled By: myleott

fbshipit-source-id: 894b104f275573ce824d7f2318d043516f0e0c5c

hubconf.py

@@ -2,16 +2,11 @@
 #
 # This source code is licensed under the MIT license found in the
 # LICENSE file in the root directory of this source tree.
+"""isort:skip_file"""
 
 import functools
 import importlib
 
-from fairseq.hub_utils import (  # noqa; noqa
-    BPEHubInterface as bpe,
-    TokenizerHubInterface as tokenizer,
-)
-from fairseq.models import MODEL_REGISTRY  # noqa
-
 
 dependencies = [
     "dataclasses",
@@ -40,6 +35,14 @@
     raise RuntimeError("Missing dependencies: {}".format(", ".join(missing_deps)))
 
 
+# only do fairseq imports after checking for dependencies
+from fairseq.hub_utils import (  # noqa; noqa
+    BPEHubInterface as bpe,
+    TokenizerHubInterface as tokenizer,
+)
+from fairseq.models import MODEL_REGISTRY  # noqa
+
+
 # torch.hub doesn't build Cython components, so if they are not found then try
 # to build them here
 try: