Bug #16315 XML: extractvalue() handles self badly

Description:
With extractvalue() there seems to be some overlapping
of self() with descendant-or-self(). If the descendants
are B+C, and self is B, then I can't see how
descendants-or-self is A+B+C.

How to repeat:
mysql> select extractvalue('<a>A<b>B<c>C</c></b></a>','/a/descendant::*');
+-------------------------------------------------------------+
| extractvalue('<a>A<b>B<c>C</c></b></a>','/a/descendant::*') |
+-------------------------------------------------------------+
| B C                                                         |
+-------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> select extractvalue('<a>A<b>B<c>C</c></b></a>','/a/self::*');
+-------------------------------------------------------+
| extractvalue('<a>A<b>B<c>C</c></b></a>','/a/self::*') |
+-------------------------------------------------------+
| B                                                     |
+-------------------------------------------------------+
1 row in set (0.00 sec)

mysql> select extractvalue('<a>A<b>B<c>C</c></b></a>','/a/descendant-or-self::*');
+---------------------------------------------------------------------+
| extractvalue('<a>A<b>B<c>C</c></b></a>','/a/descendant-or-self::*') |
+---------------------------------------------------------------------+
| A B C                                                               |
+---------------------------------------------------------------------+
1 row in set (0.00 sec)

Peter, do I understand correctly that "self" doesn't work well,
while "descendand" and "descendand-or-self" work fine? Right?

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/3301

Pushed into 5.1.8.

Thank you for your bug report. This issue has been committed to our
source repository of that product and will be incorporated into the
next release.

If necessary, you can access the source repository and build the latest
available version, including the bugfix, yourself. More information 
about accessing the source trees is available at
    http://www.mysql.com/doc/en/Installing_source_tree.html

Additional info:

Documented bugfix in 5.1.8 changelog. Closed.