Idea - fallback mode for psql backslash commands using information_schema

Hi!

I think I've got a nice TODO item for psql client:

When a client connects to a database which has unknown (newer)
version it might be advisable to 'fallback' some commands to use
INFORMATION_SCHEMA instead of system catalogs.


For instance when connected to 8.4dev server using 8.3 client,
after issuing \d foo_table you get:
ERROR:  column "reltriggers" does not exist
LINE1: SELECT relhasindex, relkind, relchecks, reltriggers, relhasr....

Of course the information_schema will probably be less efficient
and won't have PostgreSQL-specific items like 'Has OIDs', but
the user experience should be better.

My question is: does it look like a good TODO item? :)
   Best regards,        Dawid
--  ..................        ``The essence of real creativity is a certain: *Dawid Kuroczko* :         playfulness, a
flittingfrom idea to idea: qnex42@gmail.com :     without getting bogged down by fixated demands.''`..................'
Sherkaner Underhill, A Deepness in the Sky, V. Vinge