asyncio: PipeHandle.fileno() now raises an exception if the pipe is closed

Lib/asyncio/windows_utils.py

@@ -147,6 +147,8 @@ class PipeHandle:
         return self._handle
 
     def fileno(self):
+        if self._handle is None:
+            raise ValueError("I/O operatioon on closed pipe")
         return self._handle
 
     def close(self, *, CloseHandle=_winapi.CloseHandle):