Comment 0 for bug 1731296

Test Case
=========
Install Ubuntu 17.10.
sudo apt install unity
Restart your computer.
On the login screen, click your name then click the gear button and select Unity. Log in.
In the Launcher on the left side of the screen, GNOME Software is shown but not Ubuntu Software

Background Info
===============
There is an interesting per-desktop override feature. The primary .desktop is installed as /usr/share/applications/org.gnome.Software.desktop . That .desktop file can be overriden for the ubuntu desktop by shipping /usr/share/applications/Ubuntu/org.gnome.Software.desktop or for the gnome desktop by shipping /usr/share/applications/gnome/org.gnome.Software.desktop.

Until now, this override was only done for the Ubuntu session (which in 17.10 is no longer Unity).

Proposal #1
===========
Have the ubuntu-software packaging install the override .desktop to /usr/share/unity/applications/ too.

Proposal #2
===========
Have the ubuntu-software packaging install the override .desktop to /usr/share/FOO/applications/ where FOO is every desktop session in Ubuntu. Then it's up to users and flavors whether they want the Ubuntu or GNOME branding based on whether they install the ubuntu-software package.

Proposal #3
===========
Rework the packaging to install the Ubuntu Software .desktop to /usr/share/applications/
Install the GNOME Software .desktop to /usr/share/gnome/applications/ so that GNOME (as in the vanilla GNOME session) alone gets the GNOME branding.