[–] beetusvoater 0 points 2 points 2 points (+2|-0) ago (edited ago)
If all else fails, you can just specify the version you want (didn't try it, but you do it by appending a "=" and the Version you want to have.).
sudo apt-get install libreoffice=1:5.0.0~rc5-0ubuntu1~trusty1
Your problem seems to be related to pinning... I didn't look deeper into it, but you might want to if you wan to have a more permanent solution.
EDIT: checked the command and corrected it.
[–] ReverendJ1 [S] 0 points 1 point 1 point (+1|-0) ago
I wonder if Synaptic automagically fixes the pinning, and that's what's going on here.
[–] beetusvoater ago (edited ago)
No, I was mistaken. I only had the problem of not being able to add a new repo, which is really strange behaviour.
Anyway, you were right with your pinning hypothesis:
[–] ReverendJ1 [S] 0 points 1 point 1 point (+1|-0) ago
Weird. I've never ran into an issue adding a PPA. Some repos hosted elsewhere, yeah, but never a PPA from Launchpad.
Pretty interesting about the apt-pinning that Mint does, but like I said, it makes sense since it's using a base distro. I've just never seen it anywhere where it needed to be treated any differently than a regular Ubuntu box as far as adding repos goes though.