Allow lightdm to be an alternate recommends for gdm3

[Jeremy Bícha]

Impact
------
If an Ubuntu user installs gnome-shell, they will be shown a debconf prompt asking to choose between gdm3 and lightdm. No information is given as to why one or the other should be chosen.

This can be fixed by recommending gdm3 | lightdm

Test Case
---------
From Ubuntu (Unity), install gnome-shell. gdm3 should not be installed and there should be no debconf prompt.

Regression Potential
--------------------
None really. GDM does look a bit nicer with GNOME Shell than LightDM in 17.04 and older releases but if a user wants GNOME Shell to look nice, they should just install Ubuntu GNOME. It's not worth the avoidable debconf question for that.

Other Info
----------
This was already done for artful as part of the GNOME transition.

Users will still see a debconf prompt if they install ubuntu-gnome-desktop but there's not much we can do about that now in SRUs.

All Ubuntu "desktop" flavors except for Ubuntu GNOME and Kubuntu use LightDM. Kubuntu currently uses sddm, but no one has bothered to get sddm working with GNOME Shell.

[Łukasz Zemczak (sil2100)]

Hello Jeremy, or anyone else affected,

Accepted gnome-shell into zesty-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/gnome-shell/3.24.2-0ubuntu0.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, and change the tag from verification-needed to verification-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Łukasz Zemczak (sil2100)]

Hello Jeremy, or anyone else affected,

Accepted gnome-shell into yakkety-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/gnome-shell/3.20.4-0ubuntu3 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, and change the tag from verification-needed to verification-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Łukasz Zemczak (sil2100)]

Hello Jeremy, or anyone else affected,

Accepted gnome-shell into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/gnome-shell/3.18.5-0ubuntu0.3 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, and change the tag from verification-needed to verification-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Jeremy Bícha (jbicha)]

From Ubuntu (Unity) 16.04, 16.10 and 17.04, I enabled -proposed updated and installed gnome-shell and was not asked whether to pick gdm3 or lightdm. I logged out of Unity and logged into GNOME successfully.

gnome-shell 3.18.5-0ubuntu0.3 (16.04)
gnome-shell 3.20.4-0ubuntu3 (16.10)
gnome-shell 3.24.2-0ubuntu0.1 (17.04)

[Launchpad Janitor (janitor)]

This bug was fixed in the package gnome-shell - 3.18.5-0ubuntu0.3

---------------
gnome-shell (3.18.5-0ubuntu0.3) xenial; urgency=medium

  * Extend ubuntu-lightdm-user-switching.patch to allow
    locking screen using LightDM (LP: #1684205)
  * Allow lightdm to be an alternate recommends for gdm3 to avoid debconf
    question if a display manager is already installed (LP: #1690938)
  * Depend on caribou, needed for the Screen Keyboard (LP: #1589240)
  * Recommend chrome-gnome-shell, needed for Firefox, Chromium, Chrome and
    Opera to work with https://extensions.gnome.org/ (LP: #1672175)

 -- Jeremy Bicha <email address hidden> Sat, 13 May 2017 17:46:47 -0400

[Brian Murray (brian-murray)]

The verification of the Stable Release Update for gnome-shell has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

[Launchpad Janitor (janitor)]

This bug was fixed in the package gnome-shell - 3.20.4-0ubuntu3

---------------
gnome-shell (3.20.4-0ubuntu3) yakkety; urgency=medium

  * Extend ubuntu-lightdm-user-switching.patch to allow
    locking screen using LightDM (LP: #1684205)
  * Allow lightdm to be an alternate recommends for gdm3 to avoid debconf
    question if a display manager is already installed (LP: #1690938)
  * Depend on caribou, needed for the Screen Keyboard (LP: #1589240)
  * Recommend chrome-gnome-shell, needed for Firefox, Chromium, Chrome and
    Opera to work with https://extensions.gnome.org/ (LP: #1672175)

 -- Jeremy Bicha <email address hidden> Mon, 15 May 2017 18:38:18 -0400

[Launchpad Janitor (janitor)]

This bug was fixed in the package gnome-shell - 3.24.2-0ubuntu0.1

---------------
gnome-shell (3.24.2-0ubuntu0.1) zesty; urgency=medium

  * New upstream release (LP: #1690182)
  * Extend ubuntu-lightdm-user-switching.patch to allow
    locking screen using LightDM (LP: #1684205)
  * Allow lightdm to be an alternate recommends for gdm3 to avoid debconf
    question if a display manager is already installed (LP: #1690938)
  * Depend on caribou, needed for the Screen Keyboard (LP: #1589240)

 -- Jeremy Bicha <email address hidden> Mon, 15 May 2017 18:36:22 -0400