Bug#908329: lightdm: LightDM shuts down the screen on lock and won't turn it on

[Braiam Peguero <braiamp@gmail.com>]

Package: lightdm
Version: 1.26.0-2
Severity: important

Dear Maintainer,

When the greeter screen turn off, no amount of key-bashing
or mouse fiddling would turn it off. It only seems to happen
when locking the screen. VT switching allow the monitor to
turn on. I would expect lightdm to turn on the screen when
I start typing or moving the mouse as the system should show
responsiveness.

-- System Information:
Debian Release: buster/sid
  APT prefers testing
  APT policy: (500, 'testing'), (100, 'unstable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.17.0-3-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.utf8, LC_CTYPE=en_US.utf8 (charmap=UTF-8), LANGUAGE=en_US:en (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages lightdm depends on:
ii  adduser                                3.117
ii  dbus                                   1.12.10-1
ii  debconf [debconf-2.0]                  1.5.69
ii  libaudit1                              1:2.8.4-2
ii  libc6                                  2.27-5
ii  libgcrypt20                            1.8.3-1
ii  libglib2.0-0                           2.56.1-2
ii  libpam-systemd                         239-7
ii  libpam0g                               1.1.8-3.8
ii  libxcb1                                1.13-3
ii  libxdmcp6                              1:1.1.2-3
ii  lightdm-gtk-greeter [lightdm-greeter]  2.0.5-1
ii  lsb-base                               9.20170808

Versions of packages lightdm recommends:
ii  xserver-xorg  1:7.7+19

Versions of packages lightdm suggests:
pn  accountsservice  <none>
ii  upower           0.99.8-2
pn  xserver-xephyr   <none>

-- debconf-show failed