autocommit not ensured after changing user

[everpcpc]

test schema:

root@localhost [test] mysql> show create table test\G
*************************** 1. row ***************************
       Table: test
Create Table: CREATE TABLE `test` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=26 DEFAULT CHARSET=utf8

test script:

import MySQLdb


r = {
    'host': 'localhost',
    'port': 3306,
    'user': 'test1',
    'passwd': 'test1',
    'db': 'test'
}
conn = MySQLdb.connect(**r)
cursor = conn.cursor()

cursor.execute('insert into test values()')
conn.rollback()

r = {
    'host': 'localhost',
    'port': 3306,
    'user': 'test2',
    'passwd': 'test2',
    'db': 'test'
}
conn = MySQLdb.connect(**r)
cursor = conn.cursor()

cursor.execute('insert into test values()')
conn.rollback()
cursor.execute('select @@autocommit')
print(cursor.fetchall())

The latter insert statement will be committed directly instead of rolling back.

The reason is, after changing user, the autocommit on the backend will be set to default true, while last_set_autocommit is still 0 which was set during the former insert query.
So in MySQL_Connection::IsAutoCommit, it is treated as mysql issue 66884 by mistake, and assumes autocommit is false, thus not changing it on the backend.
cc @MOON-CLJ

[renecannao]

Hi @everpcpc . Thank you for the report!
Fixed in 1.4.1 and 1.3.8 .

Before the fix, with insert committed:

$ python bug1069.py
((1L,),)

After the fix, with insert rolled back:

$ python bug1069.py
((0L,),)