Tell gnus to never ever expire even expirable messages

[Arcady Genkin <antipode@thpoon.com>]

I know this is a bit of a contradiction, but I want gnus to never
expire messages in my private mail group, even if marked as
expirable.  Setting (expiry-wait quote never) in group parameters
doesn't seem to do the trick.

Here's the situation.  I'm used to unmark ticked messages in most of
my groups by pressing `E', because I want them to expire.  Sometimes,
in my private group, I unmark ticked message by pressing `E' instead
of `d' (contrary to my intention).  This is my own mistake, I know,
but is there a way to set a self-guard against this for a given group?
I've lost more than one important messages this way. ;^(
-- 
Arcady Genkin
Don't read everything you believe.