Media keys do not work in 1.4.0rc1-153-g06ba55549 Ubuntu Bionic (18.04)

Before posting

Please follow the steps below and check the boxes with [x] once you did the step.

[x] I checked the issue tracker for similar issues
[x] I checked the changelog if the issue is already resolved
[x] I tried the latest Clementine build from here

System information

Please provide information about your system and the version of Clementine used.

Operating System: Ubuntu 18.04
Clementine version: 1.4.0rc1-153-g06ba55549

Expected behaviour / actual behaviour

Expected behavior: Media keys (standard x86 media keys (Play/Pause, Stop, Next, Prev)) should work.

Actual behaviour:

There is no reaction on pressing Media keys (standard XF86 media keys (Play/Pause, Stop, Next, Prev)), also there is no any messages while running clementine --verbose when pressing keys.
But! The keys are recognized, when trying to assign them through Tools->Preferences->Configure Shortcuts, so assignment(only) works.
In custom clementine built from "qt5" branch around Oct 20 2019 (Help->About Clementine shows "Version 1.3.1-844-g6201247c0") media keys works perfectly.

Steps to reproduce the problem (only for bugs)

1) dpkg -i clementine_1.4.0rc1-153-g06ba55549.bionic_amd64.deb 2) Press Play/Pause, Stop, Next, Prev hardware buttons on your keyboard.

P.S.

Small update - Media keys do not work on any of 1.4.0 builds provided here: https://builds.clementine-player.org/ubuntu-bionic/

P.P.S

Media keys work on following revision:

git branch -v | head -n 1
* (HEAD detached at origin/qt5) 75f18dab2 Merge pull request #6374 from jonaski/qt5-update

git log -1
commit 75f18dab23f0842713a4200a7e362efd51b12e31 (HEAD, origin/qt5)
Merge: 3694bcfc8 66fdc935a
Author: John Maguire <john.maguire@gmail.com>
Date:   Wed Jul 24 11:51:48 2019 +0100

    Merge pull request #6374 from jonaski/qt5-update

    Qt5 update

clementine-player / Clementine

Media keys do not work in 1.4.0rc1-153-g06ba55549 Ubuntu Bionic (18.04) #6634