Produce correct answers for Group BY NULL (Option 1)#793

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alamb merged 2 commits intoapache:masterfrom

alamb:alamb/gby_null_alternative

Aug 2, 2021

Commits on Jul 30, 2021

Add support for group by hash of a null column, tests for same
alamb
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Update datafusion/src/physical_plan/hash_aggregate.rs

alamb
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Dandandan
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