When a table has an INTEGER PRIMARY KEY ON CONFLICT REPLACE and some other

When a table has an INTEGER PRIMARY KEY ON CONFLICT REPLACE and some other
uniqueness constraint, and it participates in an upsert on that other
constraint, ensure that code that checks for conflicts on the INTEGER PRIMARY
KEY is well-formed.  Fix for the problem reported by
[forum:/forumpost/06b16b8b29f8c8c3|forum post 06b16b8b29f8c8c3].

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