do-partial-upgrade crashed with PermissionError in setup_logging(): [Errno 13] Brak dostępu: '/var/log/dist-upgrade//20150217-1221'

ocure when dist upgrade

ProblemType: Crash
DistroRelease: Ubuntu 15.04
Package: ubuntu-release-upgrader-core 1:15.04.5
ProcVersionSignature: Ubuntu 3.18.0-13.14-generic 3.18.5
Uname: Linux 3.18.0-13-generic i686
ApportVersion: 2.16.1-0ubuntu2
Architecture: i386
CrashCounter: 1
CrashDB: ubuntu
CurrentDesktop: GNOME
Date: Tue Feb 17 12:21:19 2015
ExecutablePath: /usr/lib/ubuntu-release-upgrader/do-partial-upgrade
InstallationDate: Installed on 2014-12-10 (69 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Alpha i386 (20141209)
InterpreterPath: /usr/bin/python3.4
PackageArchitecture: all
ProcCmdline: /usr/bin/python3 /usr/lib/ubuntu-release-upgrader/do-partial-upgrade --frontend=DistUpgradeViewGtk3
ProcEnviron:
 LANGUAGE=pl_PL
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=pl_PL.UTF-8
 SHELL=/bin/bash
PythonArgs: ['/usr/lib/ubuntu-release-upgrader/do-partial-upgrade', '--frontend=DistUpgradeViewGtk3']
SourcePackage: ubuntu-release-upgrader
Title: do-partial-upgrade crashed with PermissionError in setup_logging(): [Errno 13] Brak dostępu: '/var/log/dist-upgrade//20150217-1221'
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm autopilot cdrom debian-tor dip disk libvirtd lpadmin plugdev sambashare sudo
VarLogDistupgradeTermlog: