coercions should always return a new node in order to support result reuse

Cython/Compiler/ExprNodes.py

@@ -5627,10 +5627,13 @@ class BoolBinopNode(ExprNode):
                 or self.operand2.compile_time_value(denv)
     
     def coerce_to_boolean(self, env):
-        self.operand1 = self.operand1.coerce_to_boolean(env)
-        self.operand2 = self.operand2.coerce_to_boolean(env)
-        self.type = PyrexTypes.c_bint_type
-        return self
+        return BoolBinopNode(
+            self.pos,
+            operator = self.operator,
+            operand1 = self.operand1.coerce_to_boolean(env),
+            operand2 = self.operand2.coerce_to_boolean(env),
+            type = PyrexTypes.c_bint_type,
+            is_temp = self.is_temp)
 
     def analyse_types(self, env):
         self.operand1.analyse_types(env)