cyradm mailbox creation behaving differently if using CRAM-MD5 or DIGEST-MD5 auth

[OpenMacNews]

hi all,
after building:
        cyrus-sasl-2.1.20
        cyrus-imapd-2.2.10
                w/ patches from http://email.uoa.gr/projects/cyrus/
                        cyrus-imapd-2.2.10-autocreate-0.1.diff
                        cyrus-imapd-2.2.10-rmquota-0.1.diff
                        cyrus-imapd-2.2.10-deletemailbox-0.1.diff
                        cyrus-imapd-2.2.10-autosieve-0.1.diff
on OSX 10.3.7, i'm finding cyradm behaves differently when using CRAM-MD5 vs 
DIGEST-MD5 authentication.

i've created in sasldb2 an admin user (my.admin) for my canonical domain 
(devbox.internal.testdomain.com):

% echo blahblah | saslpasswd2 -p -c -u devbox.internal.testdomain.com my.admin
veifying:
% sasldblistusers2
                [EMAIL PROTECTED]: userPassword

now, if i use cyradm with DIGEST-MD5 auth:
% cyradm --auth DIGEST-MD5 --user [EMAIL PROTECTED] 
--server devbox.internal.testdomain.com --port 143

and attempt to create a new virutal [EMAIL PROTECTED]
        devbox.internal.testdomain.com> cm [EMAIL PROTECTED]
all is OK.
        devbox.internal.testdomain.com> lm
                [EMAIL PROTECTED] (\HasNoChildren)

however, if i start over, and do the same with CRAM-MD5
% cyradm --auth CRAM-MD5 --user [EMAIL PROTECTED] 
--server devbox.internal.testdomain.com --port 143

        devbox.internal.testdomain.com> cm [EMAIL PROTECTED]
i get an ERROR:
                createmailbox: Invalid mailbox name
but, if i add the canonical domain (realm?) ...
	devbox.internal.testdomain.com> cm 
[EMAIL PROTECTED]@devbox.internal.testdomain.com

it now works as expected:
        devbox.internal.testdomain.com> lm
                [EMAIL PROTECTED] (\HasNoChildren)
############
## QUESTION
#
why the different behavior -- DIGEST-MD5 requiring the additional domain/realm? 
is this expected behavior, or a BUG?

thx!
richard
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