sound is not reenabled when unmuting (multimedia key mute)

[Horst Schirmeier]

Since using Ubuntu 13.10 and XFCE (as Gnome is completely unusable by now, but I guess that's rather a feature than a bug), pressing the "mute" multimedia key does not reenable sound after muting.

After logging into a freshly booted system, pressing the "mute" multimedia key results in:
 - The sound-indicator applet shows the "muted" symbol.
 - Sound is muted.
 - alsamixer shows that Master, Headphone and PCM switched from open (OO) to muted (MM).

Pressing the "mute" key again results in:
 - The sound-indicator applet again shows its normal state (in my case a mouseover gives "Master: 65%").
 - Still hearing no sound.
 - alsamixer shows that Master has been unmuted, but Headphone and PCM are still muted.

Expected behavior: I should be hearing sound again, Headphone and PCM should also be unmuted.

Workaround: Use alsamixer to manually unmute (navigate to Headphone and PCM, press 'M' key) channels.

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: indicator-sound 12.10.2+13.10.20131011-0ubuntu1
ProcVersionSignature: Ubuntu 3.11.0-14.21-generic 3.11.7
Uname: Linux 3.11.0-14-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.12.5-0ubuntu2.1
Architecture: amd64
Date: Sat Dec 7 16:06:15 2013
InstallationDate: Installed on 2012-07-06 (519 days ago)
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
MarkForUpload: True
SourcePackage: indicator-sound
UpgradeStatus: Upgraded to saucy on 2013-10-17 (51 days ago)