This is a similar problem to one that was earlier fixed in MySQL-5.0 under terms of:
Bug#27586 Wrong autoinc value assigned by LOAD DATA in the NO_AUTO_VALUE_ON_ZERO mode

Now for LOAD XML instead of LOAD DATA.

I put a file MYSQL_HOME_DIR/test/t1.xml with this content:

<list>

  <row a="1" b="bbb1"/>

  <row b="bbb2"/>

</list>

and run this script:

SET @@SQL_MODE=NO_AUTO_VALUE_ON_ZERO;

CREATE OR REPLACE TABLE t1(a INT AUTO_INCREMENT PRIMARY KEY, b TEXT);

LOAD XML INFILE 't1.xml' INTO TABLE t1 ROWS IDENTIFIED BY '<row>';

SELECT * FROM t1 ORDER BY b;

It returns the following data:

+---+------+

| a | b    |

+---+------+

| 1 | bbb1 |

| 0 | bbb2 |

+---+------+

The auto-increment value for the second record is wrong. It should be 2 rather than 0.