This bug caused a crash of the server at the second execution of a stored
function that used DELETE or UPDATE statement if the first execution
of this function reported an error encountered after the prepare phase.
This happened because in such cases the executed DELETE/UPDATE statement
remained marked as prepared. As a result the second execution of SF missed
the prepare phase for the statement altogether and the statement could not
be executed properly.

Approved by Oleksandr Byelkin <sanja@mariadb.com>