fcron without anacron breaks /etc/crontab

fcron's README.Debian includes the following:

> ** FCRON DOES NOT REPLACE CRON YET, KEEP CRON INSTALLED **
>
> While in principle this would be possible, the Debian
> package of fcron does not try to supersede cron. Note,
> however, that it has to play dirty with anacron so as to
> hijack control of /etc/cron.{daily,weekly,monthly} from cron
> even if anacron is not installed in the system.
>
> This is done symlinking /usr/sbin/anacron to /bin/true, and
> unfortunately causes the fcron package to conflict with the
> anacron package. If you just removed (as opposed to purging)
> the anacron package to install fcron, anacron's initscript
> might still try to activate anacron. This is harmless, do
> NOT file bugs against anacron because of it!
...
> The system fcrontab is accessible using fcrontab -e systab,
> as root. That's where the anacron-emulation lives. If you
> want to customize at which time/day of the week/day of the
> month the daily, weekly and monthly cron jobs are to be run,
> that's the place to poke at.

Regardless of that admission in the README, it reads like out of the box, fcron should work as an anacron replacement. But it doesn't. I'm seeing this behaviour also on Debian/etch, so it's a definite problem with the fcron package.

On Debian, when I try to edit the systab as indicated there using "sudo fcrontab -e systab", it throws the following PAM error:

18:37:16 Could not open PAM session: Insufficient credentials to access authentication data

So it's broken in multiple ways, and doesn't work as described OOTB.

Status changed to 'Confirmed' because the bug affects multiple users.