/etc/cron.daily/bugzilla3 fails to run sanity check if ldap authentication is used

I am running bugzilla3 on a stock lucid LTS.
Using LDAP as authentication method where the uid is a plain username like "myadmin" the cronjob running sanitycheck.pl fails:

/etc/cron.daily/bugzilla3:
The name <email address hidden> is not a valid username. Either you
misspelled it, or the person has not registered for a Bugzilla account.
run-parts: /etc/cron.daily/bugzilla3 exited with return code 9

My ADMIN_EMAIL is <email address hidden> but the login for that person is "myadmin".
However, the cronjob does extract the email address and pass this to sanitycheck.pl - this does only work if login is a email address.

[...]
admin=`perl -e "require \"$answerfile\"; print \\\$answer{'ADMIN_EMAIL'}. \"\\n\"";`
su www-data -c "/usr/share/bugzilla3/lib/sanitycheck.pl --login \"$admin\""
[...]

Login and E-Mail must not be the same persons and at least if they are, login must not be the email address - this needs to be separated.