[DRE-maint] Bug#839807: unicorn: Missing depends on lsb-base

[Santiago Vila]

Package: unicorn
Version: 5.0.1-2
Tags: patch

Dear maintainer:

This package inconditionally uses /lib/lsb/init-functions in its init
script, so it should have a "Depends: lsb-base", as lsb-base is not
essential. Patch attached.

I discovered this by using sbuild to build a package having unicorn as
one of its build-depends in a chroot not having lsb-base installed by
default. The package builds ok, but when it ends, removing the
installed packages fails in this way:

Removing unicorn (5.0.1-2) ...
invoke-rc.d: could not determine current runlevel
/etc/init.d/unicorn: 19: .: Can't open /lib/lsb/init-functions
invoke-rc.d: initscript unicorn, action "stop" failed.
dpkg: error processing package unicorn (--remove):
 subprocess installed pre-removal script returned error exit status 2

and the chroot becomes unusable and it has to be restored from tarball
again.

Thanks.