UnicodeDecodeError with SECRET_KEY not ascii

[g1ra]

Cannot handle special character.

For example:
SECRET_KEY = '\x91\x85K\xcek\xcc\xb9\x99[$)\xd9\xbc(\x96,\xb4\xcc\xdcGRC\xefz'

UnicodeDecodeError: 'ascii' codec can't decode byte 0x91 in position 0: ordinal not in range(128)
flask_login.py", line 542, in make_secure_token
key = key.encode('utf-8') # ensure bytes

[g1ra]

fix:
SECRET_KEY = u'\x91\x85K\xcek\xcc\xb9\x99[$)\xd9\xbc(\x96,\xb4\xcc\xdcGRC\xefz'