Comment 44 for bug 1710278

# Quick note before one want to test this package:
* This is a test package for others to test, ONLY made to determine that it works as expected and fixes the current situation (pre-sru).
* This is NOT a long term nor final solution yet, please wait until the package is found in the official Ubuntu archive before considering this official (Post-SRU)
* DO NOT test on production area.
* This package is subject to change as we progress.

# PPA instructions:
sudo add-apt-repository ppa:slashd/lp1710278
sudo apt-get update
sudo apt install bind9-single-thread

As I write this, the version is : 1:9.11.3+dfsg-1ubuntu1.8+hfv20190801lp1710278b2

# Testing:
* Test MAAS with DNSSEC on|off|automatic|.... with a significant amount of machines/VMs (at least 50 from what I heard/can tell)
* Validate that only bind9 or bind9-single-thread can be installed at the time on the same system (basically both bind packages can't co-exist and be co-installable at the same time/on the same machine)
- I already tested that part, and it did the trick for me but having more eyes on won't hurt.

Expected behaviour:
 - If bind9 is installed and one tries to install bind9-single-thread
"
The following packages will be REMOVED:
  bind9-single-thread
The following NEW packages will be installed:
  bind9
"
 - If bind9-single-thread is installed and one tries to install bind9:
"
The following packages will be REMOVED:
  bind9
The following NEW packages will be installed:
  bind9-single-thread
"
So that way it will conflicts, but won't block user to switch from one to another due to the "Replaces:" put in place, but users/package maintainer depending on one or the other will have to read carefully what apt will mentioned and know what they are doing here.

If you think of anything else, please do so. The more testing/feedback the better.

- Eric