pulse-audio does not restore volume to streams correctly under kernel 4.4.0-148-generic

[Jozef Behran]

This might be also bug in pulse-audio. The problem
manifests in these ways:

Scenario 1:
1. Assuming output is to a built-in speaker, set the
   volume to non-100%.
2. Connect an audio output device (e.g. headphones).
3. Set the volume to non-100% but visibly different from
   the level set at 1.
4. Disconnect the audio output device.
5. The sound volume is blasted back to 100%.
6. Connect the audio output device again. If the sound
   volume stays at 100%, go to step 3.
7. Verify that pulse audio remembers the volume level
   for the audio output device by repeatedly disconnecting
   and reconnecting it. If it does not, go to step 2.
8. Start playing some sound.
9. While the sound is playing, disconnect and then reconnect
   the audio output device. The volume level for the audio
   is again blasted at 100%

Scenario 2:
1. Set the volume level for an audio device by following
   scenario 1 until step 8 is reached.
2. Instead of "playing some sound", disconnect the audio
   output device and set the volume level (which is at
   100% now) to some non-100%-value.
3. Connect the audio output device. The volume level for
   the audio output device is blasted back at 100%

This problem disappears when the system is booted from the
original kernel version (4.4.0-31-generic). Under this kernel
pulse audio remembers the volume levels for the two streams
correctly. Therefore I assume the bug is somewhere in the
kernel. The pulse-audio package is the latest version as of
yesterday.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-4.4.0-148-generic 4.4.0-148.174~14.04.1
ProcVersionSignature: Ubuntu 4.4.0-31.50~14.04.1-generic 4.4.13
Uname: Linux 4.4.0-31-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.29
Architecture: amd64
CurrentDesktop: Unity
Date: Fri Jun 21 22:03:43 2019
InstallationDate: Installed on 2019-06-01 (20 days ago)
InstallationMedia: Ubuntu 14.04.5 LTS "Trusty Tahr" - Release amd64 (20160803)
ProcEnviron:
 TERM=xterm
 SHELL=/bin/bash
 LD_LIBRARY_PATH=<set>
 PATH=(custom, user)
 XDG_RUNTIME_DIR=<set>
SourcePackage: linux-signed-lts-xenial
UpgradeStatus: No upgrade log present (probably fresh install)