alleviate hanging issue caused by concat op

src/relay/op/tensor/transform.cc

@@ -6,9 +6,9 @@
  * to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance
  * with the License.  You may obtain a copy of the License at
- * 
+ *
  *   http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing,
  * software distributed under the License is distributed on an
  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
@@ -292,7 +292,7 @@ RELAY_REGISTER_OP("concatenate")
 .add_type_rel("Concatenate", ConcatenateRel)
 .set_attr<FInferCorrectLayout>("FInferCorrectLayout", ConcatenateLayout)
 .set_attr<FTVMCompute>("FTVMCompute", ConcatenateCompute)
-.set_attr<TOpPattern>("TOpPattern", kInjective);
+.set_attr<TOpPattern>("TOpPattern", kOpaque);
 
 TVM_REGISTER_NODE_TYPE(StackAttrs);