[c-nsp] revert redundant sups to single sup720

[randal k]

Collective Knowledge!

I have a lab 6509 with a sup720-3bxl with a single 6148A-GE in it, running
native IOS on 12.2(18).SXF7 . Once upon a time, it had dual supervisors, but
one was stolen to make our mpls lab. It complains that it does not pass the
TestFabricSnakeForward and TestFabricSnakeBackward online diagnostics.
Research tells me that this is a fabric test, and it is failing because it
is missing the secondary sup. This 6509 does perform beautifully otherwise
and has no operating issues in the past month or so - it is also a lab
device, so it gets pretty abused.

The mpls-lab-6509 does not exhibit the behavior (it's sup was the slave).

The problem router still believes that is has dual sups:

lab02.cos01# show redundancy
<snip>
                 Hardware Mode = Duplex
    Configured Redundancy Mode = sso
     Operating Redundancy Mode = sso
              Maintenance Mode = Disabled
                Communications = Down      Reason: Simplex mode

lab02.cos01# show bootvar
<snip>
Standby is not up.

Our other single-sup 6509s say "Hardware Mode = Simplex" and "Standby is not
present."

So, background established, how do I convince a once-redundant supervisor
that it is now standalone? I have searched and searched and searched and I
cannot find anything that works. The only thing I haven't tried is
offline-editing the config to remove the redundancy section and loading it
in then rebooting.

Anybody have any ideas on how to downgrade dual-sups to single sup?

Thanks!
Randal