non Aggregate expression are considered as expression of aggregation in the Split::Reduce

[vserret]

SELECT 3*d, COUNT(*) AS my_count FROM table_1 GROUP BY 3*d;
==>
Split
field_fp0x -> (3 * field_agws)
my_count -> field_i4xy
field_i4xy -> count(field_n9r3)
field_agws -> first(field_8rd1) <== this should be first(field_9e8u)
GROUP BY -> field_9e8u
field_n9r3 -> 1
field_8rd1 -> d
field_9e8u -> (3 * d)