I was going to report as a bug that this package is essential without
using Pre-Depends, but I found several reasons why the essential flag
is not needed anymore:

* The package contains a single binary, update-passwd. This binary is
used in the postinst, but it does not seem the type of binary which is
likely to be used by other packages in their maintainer scripts.

* The files /etc/passwd etc. are no longer conffiles. The package may
be purged without losing any valuable data.

* Even if the package is purged, you can easily reinstall it flawlessly
by using "apt-get install" or dpkg on the command line.

For these reasons I think it would make sense to drop the essential flag
for this package, to become "just" required.

[ However, if you truly think the update-passwd is to be used by other
packages, then please use a pre-depends, not a depends ].

Thanks.