Please use this patch instead of my previously submitted one.
It is just remerged against HEAD for new alter_table.out stuff.
Another reason this patch is useful for _interactive_ users: imagine a
view based on a many way join. Imagine creating a complicated insert
rule that inserts into all the joined tables and when you insert you get
a check failure, but you need to know which actual table the constraint
was on that failed!
Christopher Kings-Lynne
10f1f709ab