Fix cypclass refcount on arrays

Cython/Compiler/ExprNodes.py

@@ -4169,6 +4169,13 @@ class IndexNode(_IndexingBaseNode):
             code.putln(
                 "%s = %s;" % (self.result(), rhs.result()))
 
+        if self.type.is_cyp_class:
+            # This hack is due to the fact cypclass objects are ref-counted, so
+            # they goes into temps, but their assignment code is a simple C assignment,
+            # which doesn't incref the temp.
+            # So we are effectively absorbing a reference in this case.
+            rhs.generate_post_assignment_code(code)
+        else:
             self.generate_subexpr_disposal_code(code)
             self.free_subexpr_temps(code)
             rhs.generate_disposal_code(code)