lenny-backports update of dovecot-common to 1:1.2.11-1~bpo50+1 introduces dependency on libmysqlclient16

[Guido Berhoerster <guido+backports.org@berhoerster.name>]

Hello,

the recent security update of dovecot-common to
1:1.2.11-1~bpo50+1 depends on libmysqlclient16 whereas
1:1.2.9-1~bpo50+1 depended on libmysqlclient15off.
libmysqlclient16 in turn depends on mysql-common
(>= 5.1.43-1~bpo50+1), so in effect this means that in order to
install this security update people are forced to upgrade
MySQL from stable to the lenny-backports branch.
Please change the dependency back to libmysqlclient15off or
backport the security fix only.
Thanks in advance.
-- 
Guido Berhoerster