Can't upgrade cleanly from slink to potato

[Chris Butler <chrisb@sandy.force9.co.uk>]

Hi,

Trying to upgrade my slink box to today's potato doesn't work that smoothly:

# apt-get dist-upgrade
Reading Package Lists... Done
Building Dependency Tree... Done
Calculating Upgrade... Done
The following packages will be REMOVED:
  fidogate libmd5-perl libpam0g-util libstdc++2.9-dev lynx netstd newt0.25 perl perl-suid ppp-pam timezones
The following NEW packages will be installed:
  bootpc cfingerd debconf finger fortunes-min fping ftp icmpinfo libbz2 liblockfile1 libncurses5 libnewt0 libpam-modules
  libpam-runtime libpcre2 libpopt0 libssl09 libstdc++2.10 libstdc++2.10-dev liburi-perl libwrap0 lockfile-progs perl-5.005
  perl-5.005-base rdate rdist rsh-client ruptime rusers rwall rwho rwhod tcl8.0 tcpd tftp tk8.0 traceroute
The following packages have been kept back
  kbd
160 packages upgraded, 37 newly installed, 11 to remove and 1 not upgraded.
Need to get 0B/46.9MB of archives. After unpacking 29.8MB will be used.
Do you want to continue? [Y/n]
E: This installation run will require temporarily removing the essential package perl-base due to a Conflicts/Pre-Depends loop. This is often bad, but if you really want to do it, activate the APT::Force-LoopBreak option.
E: Internal Error, Could not early remove perl-base

Is this a known issue?

-- 
Chris    <chrisb@sandy.force9.co.uk>
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