Sort getting removed during optimization

[Julian Feinauer]

Hi all,

I just observed a Plan transformation that I don’t quite understand.
The Logical Plan is:

LogicalSort(sort0=[$0], dir0=[DESC])
  LogicalProject(time=[COALESCE($0, $2)], s1=[$1], s0=[$3])
    LogicalJoin(condition=[=($0, $2)], joinType=[full])
      LogicalTableScan(table=[[root, root.test.d0.s1]])
      LogicalTableScan(table=[[root, root.vehicle.d0.s0]])

And the result of the Volcano Planner is

BindableProject(time=[COALESCE($0, $2)], s1=[$1], s0=[$3])
  BindableJoin(condition=[=($0, $2)], joinType=[full])
    BindableTableScan(table=[[root, root.test.d0.s1]])
BindableTableScan(table=[[root, root.vehicle.d0.s0]])

I know wonder, why the LogicalSort is removed from the planner as the Output of 
the Join is NOT sorted (for a full join, for a left join it would be fine as 
the input table is sorted).

Is there anything I am missing or is this probably a Bug?

Thanks already!
Julian