windows: test sympref failing with unicodeescape error

[cbm755]

    exec(open("C:\Users\cbm\AppData\Roaming\octave\api-v59\packages\symbolic-3.1.1\private\python_header.py").read()); exec("
try:\n    _ins = []\n    _ins.append(1)  # int type\n    # end of a list\n    octoutput_drv(\"PYTHON: successful variable imp
ort\")\nexcept:\n    echo_exception_stdout(\"while copying variables to Python\")\n    raise"); exec("def _fcn(_ins):\n    _o
uts = []\n    try:\n        return Integer(_ins[0])\n    except Exception as e:\n        ers = type(e).__name__ + \": \" + st
r(e) if str(e) else type(e).__name__\n        _outs = (\"COMMAND_ERROR_PYTHON\", ers, sys.exc_info()[-1].tb_lineno)\n    retu
rn _outs\n_outs = _fcn(_ins)"); exec("try:\n    octoutput_drv(_outs)\nexcept:\n    echo_exception_stdout(\"while copying vari
ables from Python\")\n    raise");
                                                                                                            ^
SyntaxError: (unicode error) 'unicodeescape' codec can't decode bytes in position 2-3: truncated \UXXXXXXXX escape

I guess this is the C:\Users giving a \U....