Fix TF LED/Longformer attentions computation (#10007)

* Fix test

* Remove commented test

* Fix name

* Apply style

* Fix check copies

* Remove prints

* Restore boolean

* Fix reshape

tests/test_modeling_tf_longformer.py

@@ -339,15 +339,8 @@ class TFLongformerModelTest(TFModelTesterMixin, unittest.TestCase):
 
     @slow
     def test_saved_model_with_attentions_output(self):
-        # This test don't pass because of the error:
-        # condition [13,8,4,5], then [13,8,4,5], and else [13,8,4,6] must be broadcastable
-        # This occurs line 323 in modeling_tf_led.py because the condition line 255
-        # returns a tensor of shape
-        # [batch_size, seq_len, self.num_heads, self.one_sided_attn_window_size * 2 + 2]
-        # if is_global_attn is True and a tensor of shape
-        # [batch_size, seq_len, self.num_heads, self.one_sided_attn_window_size * 2 + 1]
-        # This is due to the tf.concat call line 703 that adds one dimension
-        # Need to check with PVP how to properly fix this
+        # Temporarily disable this test in order to find
+        # how to better handle it without timing out the CI
         pass
 
     @slow
@@ -371,7 +364,7 @@ class TFLongformerModelTest(TFModelTesterMixin, unittest.TestCase):
         pass
 
     def test_xla_mode(self):
-        # TODO JP: Make Blenderbot XLA compliant
+        # TODO JP: Make Longformer XLA compliant
         pass