[tests] authproxy.py: tidy up __init__()

Author: jnewbery

test/functional/test_framework/authproxy.py

@@ -71,19 +71,9 @@ def __init__(self, service_url, service_name=None, timeout=HTTP_TIMEOUT, connect
         self._service_name = service_name
         self.ensure_ascii = ensure_ascii  # can be toggled on the fly by tests
         self.__url = urllib.parse.urlparse(service_url)
-        if self.__url.port is None:
-            port = 80
-        else:
-            port = self.__url.port
-        (user, passwd) = (self.__url.username, self.__url.password)
-        try:
-            user = user.encode('utf8')
-        except AttributeError:
-            pass
-        try:
-            passwd = passwd.encode('utf8')
-        except AttributeError:
-            pass
+        port = 80 if self.__url.port is None else self.__url.port
+        user = None if self.__url.username is None else self.__url.username.encode('utf8')
+        passwd = None if self.__url.password is None else self.__url.password.encode('utf8')
         authpair = user + b':' + passwd
         self.__auth_header = b'Basic ' + base64.b64encode(authpair)