python2.7.12 ProgrammingError err, str(err) occur an error UnicodeEncodeError: 'ascii' codec can't encode character

[bloodwolf2020]

i use this in twisted, when sql contain chinese, i exec sql like this:
"select * from test where name = '\xe4\xbd\xa0\xe5\xa5\xbd'"
when table test don't have column [name], an error occur:
ProgrammingError(u'column "name" does not exist\nLINE 1: select * from test where name = '\u4f60\u597d'\n
but in twisted:
def safe_str(o):
"""
Returns a string representation of an object, or a string containing a
traceback, if that object's str raised an exception.

@param o: Any object.

@rtype: C{str}
"""
if _PY3 and isinstance(o, bytes):
    # If o is bytes and seems to holds a utf-8 encoded string,
    # convert it to str.
    try:
        return o.decode('utf-8')
    except:
        pass
try:
    return str(o)
except:
    return _safeFormat(str, o)

last error is 

i must check error.message when an error occur, so i have change code like this: