Bug #78285 Connector/Python transforms 'localhost' to '127.0.0.1' - access denied error.

Description:
So i have in MySQL 'tst'@'localhost' user:

[root@centos-base ~]# mysql -u tst -p --host='localhost'
Enter password: 
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 49
Server version: 5.5.44-MariaDB-log MariaDB Server

Copyright (c) 2000, 2015, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> \q

[root@centos-base ~]# mysql -u tst -p --host='127.0.0.1'
Enter password: 
ERROR 1045 (28000): Access denied for user 'tst'@'127.0.0.1' (using password: YES)

When i used it in a script:

import mysql.connector
from mysql.connector import errorcode

def check_mysql_flush_log_user():

        # Creating test Database and user for flushing binary logs.

        # Connection Settings

        config = {

            'user': 'tst',
            'password': '12345',
            'host': 'localhost',
#            'database': 'mysql',
            'raise_on_warnings': True,

        }

        # Open connection
        try:
            cnx = mysql.connector.connect(**config)
            cursor = cnx.cursor()
            query1 = "create database if not exists bck"
            print("Creating Test User (test_backup)+-+-+-+-+-+-+-+-+-++-+-+-+-+-OK")
            time.sleep(2)
            print("Creating Test Database (bck)+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-OK")
            cursor.execute(query1)
            cursor.close()
            cnx.close()

            return True
        except mysql.connector.Error as err:
            if err.errno == errorcode.ER_ACCESS_DENIED_ERROR:
                #print("Something is wrong with your user name or password!!!")
                print(err)
                return False
            elif err.errno == errorcode.ER_BAD_DB_ERROR:
                print("Database does not exists")
                return False
            elif err.errno == errorcode.ER_DB_CREATE_EXISTS:
                print("Database Already exists")
                return True
            else:
                print(err)
                return False

check_mysql_flush_log_user()

[root@centos-base ~]# /opt/Python-3.3.2/bin/python3 test_connection.py
1045 (28000): Access denied for user 'tst'@'127.0.0.1' (using password: YES)

It is using '127.0.0.1' even if explicitly specifying 'localhost'.

How to repeat:
1. create user 'tst'@'localhost' identified by '12345';
grant all on *.* to 'tst'@'localhost';

2. Try to connect to MySQL using Python code above. using 'host':'localhost'

Suggested fix:
Workaround is creating same user with '127.0.0.1'.

Hello Shahriyar Rzayev,

Thank you for the bug report.
I could not repeat the issue at my end using Connector / Python 2.1.3 and not seeing any issues to connecting database.
And it seems your database user doesn't have sufficient privileges. Please check user privileges.
Manual for user privileges: http://dev.mysql.com/doc/refman/5.7/en/adding-users.html

Thanks,
Chiranjeevi.

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