First entered password at lockscreen is always wrong after screen was turned off after inactivity

[janot]

1) The release of Ubuntu you are using, via 'lsb_release -rd' or System -> About Ubuntu
15.04 (This bug was also present on 14.04 and 14.10)
2) The version of the package you are using, via 'apt-cache policy pkgname' or by checking in Software Center
3.6.1-0ubuntu16
3) What you expected to happen
Screen should be unlocked
4) What happened instead
I see message about wrong password (but password is definitely entered correctly)
After that I enter it again and it's finally unlocked

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: gnome-screensaver 3.6.1-0ubuntu16
Uname: Linux 4.0.0-040000rc6-generic x86_64
ApportVersion: 2.17-0ubuntu1
Architecture: amd64
CurrentDesktop: Unity
Date: Thu Apr 9 00:15:10 2015
GnomeSessionIdleInhibited: No
GnomeSessionInhibitors: None
GsettingsGnomeSession:
 org.gnome.desktop.session session-name 'ubuntu'
 org.gnome.desktop.session idle-delay uint32 300
InstallationDate: Installed on 2014-08-18 (233 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
SourcePackage: gnome-screensaver
UpgradeStatus: No upgrade log present (probably fresh install)
mtime.conffile..etc.xdg.autostart.gnome.screensaver.desktop: 2015-02-23T22:15:30.972841

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Lysenko Denis (pharmasolin)]

I have tested this yesterday, and i don't have this issue, may be because i have 4 digit password on system i have tested on, and i'm entering password on numpad?

gnome-screensaver: Installed: 3.6.1-0ubuntu16
Ubuntu 15.04, Unity DE