Do not set jinja propagate method in MessagePassing.__init__ twice (#9198)

Author: rusty1s

torch_geometric/nn/conv/message_passing.py

@@ -240,6 +240,7 @@ def __init__(
         self._apply_sigmoid: bool = True
 
         # Inference Decomposition:
+        self._decomposed_layers = 1
         self.decomposed_layers = decomposed_layers
 
     def reset_parameters(self) -> None:
@@ -743,6 +744,9 @@ def decomposed_layers(self, decomposed_layers: int) -> None:
             raise ValueError("Inference decomposition of message passing "
                              "modules is only supported on the Python module")
 
+        if decomposed_layers == self._decomposed_layers:
+            return  # Abort early if nothing to do.
+
         self._decomposed_layers = decomposed_layers
 
         if decomposed_layers != 1:
@@ -767,6 +771,9 @@ def explain(self, explain: Optional[bool]) -> None:
             raise ValueError("Explainability of message passing modules "
                              "is only supported on the Python module")
 
+        if explain == self._explain:
+            return  # Abort early if nothing to do.
+
         self._explain = explain
 
         if explain is True: