'on insert do instead' rule with a where clause responds 'INSERT 0 0'

Hi,

Attached is the example script 'repro.sql' which creates two relations
tab1 and tab2. It also creates a rule on tab1 which simply does insert
into tab2. The insert statement into tab1 is executed afterwards. It
responds with 'INSERT 0 1'. However if I would create the same rule with
the where clause the response to the same insert statement is 'INSERT 0
0'. The output of the script executed through psql is in 'repro.out'.

Is this a bug? Is there any reason why the second insert should respond
'INSERT 0 0' instead of 'INSERT 0 1'? Thanks.

Cheers

Julo