Fix leaking a RuntimeError objects when creating sub-interpreters

Objects/exceptions.c

@@ -2093,6 +2093,7 @@ _PyExc_Init(void)
 
     preallocate_memerrors();
 
+    if (!PyExc_RecursionErrorInst) {
         PyExc_RecursionErrorInst = BaseException_new(&_PyExc_RuntimeError, NULL, NULL);
         if (!PyExc_RecursionErrorInst)
             Py_FatalError("Cannot pre-allocate RuntimeError instance for "
@@ -2115,6 +2116,7 @@ _PyExc_Init(void)
                 Py_FatalError("init of pre-allocated RuntimeError failed");
             Py_DECREF(args_tuple);
         }
+    }
 
     Py_DECREF(bltinmod);
 }