apt - How to get a repository to override all other repositories, for all software in that repository?

1. How do I get a specific repository to override all other repositories, for ALL software in that one repository? (At all times, no matter what any other repository does.)


2. After solving question 1, what is needed to get the system back to the original state (regarding LibreOffice, see Background).

Desires:

• All solutions are from the command line.


• You actually use, or have used, the solution you’re giving. (see Reference Notes)

Background:

Official 14.04 recently updated LibreOffice, causing the official repositories to install over and override the LibreOffice PPA, error message is:

# apt-get update
# apt-get upgrade

... snip ...

You might want to run 'apt-get -f install' to correct these.
The following packages have unmet dependencies:
 libreoffice-calc : Depends: libreoffice-base-core (= 1:5.4.1~rc2-0ubuntu0.14.04.1~lo0) but 1:5.4.2~rc2-0ubuntu0.14.04.1~lo1 is installed

                    Depends: libreoffice-core (= 1:5.4.1~rc2-0ubuntu0.14.04.1~lo0) but 1:5.4.2~rc2-0ubuntu0.14.04.1~lo1 is installed
 libreoffice-core : Breaks: libreoffice-calc (< 1:5.4.2~rc2-0ubuntu0.14.04.1~lo1) but 1:5.4.1~rc2-0ubuntu0.14.04.1~lo0 is installed
                    Breaks: libreoffice-draw (< 1:5.4.2~rc2-0ubuntu0.14.04.1~lo1) but 1:5.4.1~rc2-0ubuntu0.14.04.1~lo0 is installed
                    Breaks: libreoffice-impress (< 1:5.4.2~rc2-0ubuntu0.14.04.1~lo1) but 1:5.4.1~rc2-0ubuntu0.14.04.1~lo0 is installed
 libreoffice-draw : Depends: libreoffice-core (= 1:5.4.1~rc2-0ubuntu0.14.04.1~lo0) but 1:5.4.2~rc2-0ubuntu0.14.04.1~lo1 is installed
 libreoffice-impress : Depends: libreoffice-core (= 1:5.4.1~rc2-0ubuntu0.14.04.1~lo0) but 1:5.4.2~rc2-0ubuntu0.14.04.1~lo1 is installed
E: Unmet dependencies. Try using -f.

System will now not update anything until this is resolved.

Reference Notes:

Based upon How to only install updates from a specific repository?, pinning is not the answer. APT preference may be, but I’m highly hesitant to use examples found as they contradict each other and even the Debian wiki for it:

This page has been written by ZugSchlus, who not even remotely grasps
the concept of pinning. So, please take the words "probably", "needs
to be verified" and similiar wordings literally, and document your
findings (may they be "this page is right" or "this page is wrong",

optionally "this page is wrong because") here.

Further information at: https://bugs.launchpad.net/ubuntu/+source/libreoffice/+bug/1722932