DEV/FARRAGO:  fix a problem with bare nulls which showed        up during merge due to optimizer changes
DEV/FARRAGO:  fix a problem with bare nulls which showed
       up during merge due to optimizer changes

[git-p4: depot-paths = "//open/dev/": change = 5856]

LucidDB/luciddb,LucidDB/luciddb,LucidDB/luciddb,LucidDB/luciddb,LucidDB/luciddb,LucidDB/luciddb,LucidDB/luciddb,LucidDB/luciddb,LucidDB/luciddb