I have the same problem in Russian locale.
Adding "oem" encoding in the decode method solve problem with decoding but got:
File "C:\Users\User\Documents\Projects\cpython\lib\test\libregrtest\win_utils.py", line 98, in getloadavg
load = float(toks[1].replace('"', ''))
ValueError: could not convert string to float
In typeperf_output text with description of the error:
'\r\nВыполняется выход, подождите... \r\nОшибка: Счетчики не указаны.\r\n\r\r'
Translation on English is "Exiting, wait... Error: Counters are not specified."
Is it possible to check if the counters are found in advance?