This should fix a bug where a row that was updated or

        This should fix a bug where a row that was updated or
deleted that had another row inserted/updated to its old
value during the same statement or other statements before the
integrity check for noaction would incorrectly error.  This
could happen in deferred constraints or due to triggers or
functions. It's effectively a reworking of the previous patch that
did a not exists to instead do a separate check.

Stephan Szabo