read mail from disabled nnml group

[Frank Fredstone]

I've stopped using gnus for reading mail and I've set mail-sources and
nnmail-spool-file to nil, but I still want to look at the mail I had
in groups. If I try to enter the group I get an error that I'm trying
to select a non-existent method, or something to that effect.

I initially tried just commenting out the secondary select method, but
gnus would still read in my mail spool when I'd start gnus.

So, how can I not have GNUS retrieve mail from my mail spool, but
still allow me to look at the mail groups?