All Delta is droppable
* Droppable (no related upgrade paths left)
  - Drop upstart conffiles no longer shipped.
  - On transition from former versions the content of /etc/defaults/nis would be
    deleted. This patch adds preinst/postinst handling to avoid that. After this
    version the file is part of conffiles and thereby handled automatically
* Droppable (fixed upstream in 1.29.91)
  - ypbind-mt-1.20.1/src/Makefile.am: (LP: #771034, Closes: #631628)
    put libraries in ypbind_LDADD instead of AM_LDFLAGS to fix FTBFS
    with ld --as-needed. Patch submitted to Debian but not yet applied.
* Droppable (in Debian)
  - Newer build systems (>= xenial) need to have a compat level defined

  
Extra manual Tests done:
1. setup working env
2. upgrade to is
3. verify

2x lxc zesty guests

/etc/hosts
10.0.4.47 zesty-nis-server
10.0.4.18 zesty-nis-client

apt install nis
NIS Domain: zesty-nis

/etc/hosts.allow

/etc/yp.conf
- one as client one as server

/etc/ypserv.securenets
host 10.0.4.47
host 10.0.4.18

/ect/yp.conf
domain zesty-nis server 10.0.4.47

/ect/hosts.allow
portmap ypserv ypbind : 10.0.4.47 10.0.4.18

On server:
$  /usr/lib/yp/ypinit -m
$ service rpcbind restart
$ service nis restart
On client:
$ service rpcbind restart
$ service nis restart

Test (minimal)
On both:
ypcat passwd

Run yptest on both
$ yptest
# there is a known (like forever) upstream issue on the match case, don't mind that one

Add a user on the host:
$ useradd -m testuser
$ passwd testuser

Generate into nis
$ cd /var/yp
$ make

Test again with ypcat and yptest
In yptest first and next user should have changed

Restart nis and test again

=> All worked as expected