This bug was fixed in the package gdm3 - 3.29.90-1ubuntu1

---------------
gdm3 (3.29.90-1ubuntu1) cosmic; urgency=medium

  * Merge with Debian (LP: #1785789). Remaining changes:
    + README.Debian: update for correct paths in Ubuntu
    + control.in:
      - Don't recommend desktop-base
      - Depend on bash for ubuntu_config_error_dialog.patch
      - Update Vcs field
    + rules:
      - Don't override default user/group
      - --enable-gdm-xsession to install upstream Xsession script
      - override dh_installinit with --no-start to avoid session being killed
    + rules, README.Debian, gdm3.8.pod:
      Use upstream custom.conf instead of daemon.conf
    + gdm3.{postinst,postrm}: rename user and group back to gdm
    + gdm3.postinst, gdm3.prerm: don't kill gdm on upgrade
    + gdm3.*.pam: Make pam_env read ~/.pam_environment
    + gdm3.install:
      - Stop installing default.desktop. It adds unnecessary clutter
        ("System Default") to the session chooser.
      - Don't install debian/Xsession
    + Add ubuntu_run_xsession.d.patch
    + Add ubuntu_xresources_is_a_dir.patch
      - Fix loading from /etc/X11/Xresources/*
    + Add ubuntu_nvidia_prime.patch:
      - Add hook to run prime-offload (as root) and prime-switch if
        nvidia-prime is installed
    + Add revert_override_LANG_with_accountservices.patch:
      - On Ubuntu accountservices only stores the language and not the
        full locale as needed by LANG.
    + Add ubuntu_dont_set_language_env.patch:
      - Don't run the set_up_session_language() function, since it
        overrides variable values set by ~/.pam_environment
    + Add ubuntu_config_error_dialog.patch:
      - Show warning dialog in case of error in ~/.profile etc. and
        don't let a syntax error make the login fail
    + Add debian/default.pa
      - Disable Bluetooth audio devices in PulseAudio from gdm3.
    + debian/gdm3.install
      - Added details of the default.pa file
    + debian/gdm3.postinst
      - Added installation of default.pa and creation of dir if it doesn't
        exist.
    + debian/greeter.dconf-defaults: Don't set Debian settings in the
      greeter's dconf DB
  * debian/patches/unblock-sigusr1.patch: Drop, included in 3.29.90.
  * debian/patches/ubuntu_*: Refresh.
  * Merge some unreleased changes from Debian's git:
    + debian/gbp.conf: Don't use patch numbers
    + d/p/local-display-factory-add-more-debug-messages-to-new-vt-h.patch,
      d/p/local-display-factory-don-t-start-two-greeters-at-startup.patch,
      d/p/session-worker-don-t-switch-VTs-if-we-re-already-on-the-r.patch:
      Cherry-pick some patches from upstream MR 28. These fix a race condition
      on startup where GDM would try to start two greeters, and often fail to
      start any.

gdm3 (3.29.90-1) experimental; urgency=medium

  * Team upload
  * New upstream development release
    - Unblock SIGUSR1 before PAM (Closes: #905277, LP: #1782152)
  * Rebase patch series
    - Drop patches from 3.28.2-2 and 3.28.2-3, applied upstream
  * Bump GLib build-dependency to 2.44 as per configure.ac
  * Build-depend on gettext 0.19.8 as per configure.ac
  * Continue to build-depend on intltool even though upstream code no
    longer needs it, because the Debian build still does
  * Drop obsolete build-dependencies on Xft and Xi
  * Stop disabling split authentication, which is no longer supported
    at all
  * Stop deleting data/gdm.schemas.in during clean. It used to be generated
    from data/gdm.schemas.in.in but is now a source file in its own right.
  * Remove generated file data/61-gdm.rules during clean
  * d/copyright: Update
  * d/patches/*: Add DEP-3 metadata in gbp-pq format
  * d/docs: Install README.md instead of README

 -- Iain Lane <email address hidden>  Wed, 08 Aug 2018 13:11:05 +0100