Change order of io.UnsupportedOperation base classes.

This makes tests passing after changes by issue #5322.

Lib/_pyio.py

@@ -276,7 +276,7 @@ class OpenWrapper:
 try:
     UnsupportedOperation = io.UnsupportedOperation
 except AttributeError:
-    class UnsupportedOperation(ValueError, OSError):
+    class UnsupportedOperation(OSError, ValueError):
         pass
 
 

Modules/_io/_iomodule.c

@@ -654,7 +654,7 @@ PyInit__io(void)
     /* UnsupportedOperation inherits from ValueError and IOError */
     state->unsupported_operation = PyObject_CallFunction(
         (PyObject *)&PyType_Type, "s(OO){}",
-        "UnsupportedOperation", PyExc_ValueError, PyExc_IOError);
+        "UnsupportedOperation", PyExc_OSError, PyExc_ValueError);
     if (state->unsupported_operation == NULL)
         goto fail;
     Py_INCREF(state->unsupported_operation);