Address Guido's suggestion

Author: corona10

Tools/cases_generator/generate_cases.py

@@ -250,7 +250,7 @@ def assign(self, dst: StackEffect, src: StackEffect):
             self.emit(f"Py_XSETREF({dst.name}, {cast}{src.name});")
         else:
             stmt = f"{dst.name} = {cast}{src.name};"
-            if src.cond:
+            if src.cond and src.cond != "0":
                 stmt = f"if ({src.cond}) {{ {stmt} }}"
             self.emit(stmt)