Merge lp://qastaging/~fginther/livecd-rootfs/xenial-proposed-minimal-update into lp://qastaging/~ubuntu-core-dev/livecd-rootfs/xenial-proposed

Short of breaking xxd out of vim-common in xenial I don't see an alternative.... But I tested installation of vim-common on a recent xenial minimal lxd image. Installing vim-common (and friends) use 35MB of additional disk space. :-(

# apt-get install vim-common
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
  libpython3.5 vim vim-runtime
Suggested packages:
  ctags vim-doc vim-scripts vim-gnome-py2 | vim-gtk-py2 | vim-gtk3-py2 | vim-athena-py2 | vim-nox-py2
The following NEW packages will be installed:
  libpython3.5 vim vim-common vim-runtime
0 upgraded, 4 newly installed, 0 to remove and 0 not upgraded.
Need to get 7663 kB of archives.
After this operation, 35.0 MB of additional disk space will be used.

Pollinate only adds 54.3Kb to the installation on top of this.

I think 35MB is a lot to add AND I think that users will see vim on xenial and believe that it is a regression on bionic to have it gone. But I don't like the lack of pollinate so I'm going to abstain.

xxd is used in the hash_and_write function which is used in a single place in pollinate. Can xxd usage be replaced?

@rcj, in this case, the size delta is not that high. We're not actually installing vim-common into the image, we're just not removing it. vim is still being removed. As a result the difference is really the same as installing pollinate and vim-common into the current xenial minimal image with --no-install-recommends. In which case the image grows by 431K:

root@xenial-minimal:~# apt-get install --no-install-recommends pollinate
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
  gettext-base libasprintf0v5 libfreetype6 libpng12-0
Use 'apt autoremove' to remove them.
The following additional packages will be installed:
  vim-common
Suggested packages:
  vim-gnome-py2 | vim-gtk-py2 | vim-gtk3-py2 | vim-athena-py2 | vim-nox-py2
Recommended packages:
  vim | vim-gnome | vim-gtk | vim-gtk3 | vim-athena | vim-nox | vim-tiny
The following NEW packages will be installed:
  pollinate vim-common
0 upgraded, 2 newly installed, 0 to remove and 0 not upgraded.
Need to get 116 kB of archives.
After this operation, 431 kB of additional disk space will be used.

Francis, would you change your patch to keep the purge lines as they are but add pollinate and vim-common back with --no-recommends after these lines? I'd like it to be clear that we don't want vim-common but just want pollinate and have to pull in only vim-common. And it keeps the purge common across releases for any other SRUs.

I was going to suggest that we still do 'apt-mark auto vim-common' so that if anyone dist-upgrades between releases, vim-common could be marked for removal. However, it still won't be autoremoved by apt because newer pollinate depends xxd | vim-common, which would be enough to hold vim-common on the system, so it doesn't matter.

also, now that this is pollinate being reinstalled with apt, vim-common will be marked auto anyway.