The standard http basic authorization is

basic-credentials = "Basic" SP basic-cookie

basic-cookie      = <base64 [5] encoding of userid-password,
                            except not limited to 76 char/line>

userid-password   = [ token ] ":" *TEXT

but the logging/handlers module do the fllowing:

s = ('u%s:%s' % self.credentials).encode('utf-8')

s = 'Basic ' + base64.b64encode(s).strip()

why there is a redundant chr 'u'?