CREATE UNIQUE INDEX USING HASH malfunctions for engine=Aria table

On a recent trunk version (0308de9), the creation of the following index seems to malfunction:

CREATE TABLE t0(c0 INT) engine=Aria;

CREATE UNIQUE INDEX i0 USING HASH ON t0(c0); -- Key/Index cannot be defined on a virtual generated column

This error is not triggered if the index is not unique, or when "USING HASH" is not used. The error seems unexpected, because from a user perspective, no virtual generated column is involved.