Message 165157 - Python tracker

And possibly change the except clause. The except clause at PyShell 1245 was 'pass', which masked the issue of #13532 and was changed to 'raise' to effectively remove the try: except: to make the unknown problem more visible. It should perhaps be really removed if and when all calls to PyShell.write(s) are properly guarded to make sure 's' is writable.