Dear virtuoso maintainers,

When I try to install virtuoso-opensource-6.1 in a clean sid pbuilder chroot
with debconf enabled (DEBIAN_FRONTEND=readline), it prompts me for an
administrative password during installation.

However, right after I enter the password twice, it reports that it was unable
to set the password:

  Two users ("dba" and "dav") are created by default, with administrative access
  to Virtuoso. Secure passwords must be chosen for these users in order to
  complete the installation.

  If you leave this blank, the daemon will be disabled unless a non-default
  password already exists.

  Password for DBA and DAV users: /* I enter a password */

  Administrative users password confirmation: /* I enter it again */

  invoke-rc.d: policy-rc.d denied execution of start.
  Unable to set password for the Virtuoso DBA user

  An error occurred while setting the password for the Virtuoso administrative
  user. This may have happened because the account already has a password, or
  because of a communication problem with the Virtuoso server.

It is worth noting that during package remove a similar error from invoke-rc.d
is printed:

  invoke-rc.d: policy-rc.d denied execution of stop.

The full installation log is attached.

Severity is important because one may expect that on a clean system installation
works successfully. This error can also confuse users for whom virtuoso is
installed as a dependency of some other package (i.e. soprano).