Strange behavior of constraint manager for instance bus

 Hi

I am trying to create constraints on a top level cell which contains some instance buses in it.
for nets in the top level and for nets in subcell which are not bused instances, the selection works fine and I am able to create constraints correctly. However if I go down an instance bus and select a net from there, when creating constraint for that net at top level cell it creates constraint with member name 'a' and not the actual name.

For example,

Top Cell: MyTopCell
sub cells: subcell1 -> i1, subcell2 -> i2<7:0> (instance bus)

Creating constraint on i1/net1 for MyTopCell works fine
Creating constraint on i2<3>/foo for MyTopCell results in out-of-context constraint created with net name as 'a'

in CIW I see following message
*WARNING* (CMGR-1808): Constraint member of type net is out-of-context because net 'a' does not exist in the original schematic design hierarchy.

Is this intended behavior of constraint manager or a bug in tracing hierarchy for instance bus ?

Thanx,
Rush