INSERT .. SELECT .. ON DUPLICATE KEY UPDATE col=DEFAULT

In order to get correct values from update fields that
belongs to the SELECT part in the INSERT .. SELECT .. ON
DUPLICATE KEY UPDATE statement, the server adds referenced
fields to the select list. Part of the code that does this
transformation is shared between implementations of
the DEFAULT(col) function and the DEFAULT keyword (in
the col=DEFAULT expression), and an implementation of
the DEFAULT keyword is incomplete.