Comment # 4 on bug 902352 from Martin Pluskal

Issue occured again, bt looks same to me (see
http://pastebin.com/raw.php?i=r8m6g5ND for details), also this time I have
noticed following in journal:
...
Feb 18 20:12:47 dagon org.opensuse.Snapper[833]: terminate called after
throwing an instance of
'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::lock_error>
>'
Feb 18 20:12:47 dagon org.opensuse.Snapper[833]: what():  boost: mutex lock
failed in pthread_mutex_lock: Invalid argument
Feb 18 20:12:47 dagon systemd-coredump[26342]: Process 27668 (snapperd) dumped
core.

and snapper log from time issue occurred:
2015-02-18 20:11:36 MIL libsnapper(27668) Snapper.cc(Snapper):81 - Snapper
constructor
2015-02-18 20:11:36 MIL libsnapper(27668) Snapper.cc(Snapper):82 - libsnapper
version 0.2.5
2015-02-18 20:11:36 MIL libsnapper(27668) Snapper.cc(Snapper):83 -
config_name:root disable_filters:false
2015-02-18 20:11:36 MIL libsnapper(27668) AsciiFile.cc(reload):114 - loading
file /etc/snapper/configs/root
2015-02-18 20:11:36 MIL libsnapper(27668) AsciiFile.cc(getValue):228 -
key:SUBVOLUME value:/
2015-02-18 20:11:36 MIL libsnapper(27668) AsciiFile.cc(getValue):228 -
key:FSTYPE value:btrfs
2015-02-18 20:11:36 MIL libsnapper(27668) AsciiFile.cc(getValue):228 -
key:SYNC_ACL value:no
2015-02-18 20:11:36 MIL libsnapper(27668) Snapper.cc(Snapper):101 - subvolume:/
filesystem:btrfs
2015-02-18 20:11:36 MIL libsnapper(27668) Snapper.cc(loadIgnorePatterns):152 -
number of ignore patterns:8
2015-02-18 20:11:36 MIL libsnapper(27668) Snapshot.cc(read):276 - found 87
snapshots
2015-02-18 20:11:36 MIL libsnapper(27668) SystemCmd.cc(SystemCmd):46 -
constructor SystemCmd:"/usr/lib/snapper/plugins/grub --refresh"
2015-02-18 20:11:36 MIL libsnapper(27668) SystemCmd.cc(execute):82 - SystemCmd
Executing:"/usr/lib/snapper/plugins/grub --refresh"
2015-02-18 20:11:41 MIL libsnapper(27668) SystemCmd.cc(doExecute):267 -
stopwatch 4.422308s for "/usr/lib/snapper/plugins/grub --refresh"
2015-02-18 20:11:41 MIL libsnapper(27668) SystemCmd.cc(doExecute):287 -
system() Returns:0
2015-02-18 20:11:41 ERR libsnapper(27668) FileUtils.cc(SDir):89 - open failed
path://.snapshots/2651 (No such file or directory)
2015-02-18 20:11:41 MIL libsnapper(27668) SystemCmd.cc(SystemCmd):46 -
constructor SystemCmd:"/usr/lib/snapper/plugins/grub --refresh"
2015-02-18 20:11:41 MIL libsnapper(27668) SystemCmd.cc(execute):82 - SystemCmd
Executing:"/usr/lib/snapper/plugins/grub --refresh"
2015-02-18 20:11:46 MIL libsnapper(27668) SystemCmd.cc(doExecute):267 -
stopwatch 4.442388s for "/usr/lib/snapper/plugins/grub --refresh"
2015-02-18 20:11:46 MIL libsnapper(27668) SystemCmd.cc(doExecute):287 -
system() Returns:0
2015-02-18 20:11:46 MIL libsnapper(27668) AsciiFile.cc(getValue):228 -
key:BACKGROUND_COMPARISON value:yes
2015-02-18 20:11:46 MIL libsnapper(27668) Comparison.cc(Comparison):56 -
num1:2650 num2:2651
2015-02-18 20:11:46 MIL libsnapper(27668) Comparison.cc(load):167 - num1:2650
num2:2651
2015-02-18 20:11:46 MIL libsnapper(27668) Comparison.cc(create):138 - num1:2650
num2:2651
2015-02-18 20:11:46 MIL libsnapper(27668) Btrfs.cc(cmpDirs):1295 - special
btrfs cmpDirs
2015-02-18 20:11:46 MIL libsnapper(27668) Btrfs.cc(process):1266 -
dir1:'//.snapshots/2650/snapshot' dir2:'//.snapshots/2651/snapshot'
2015-02-18 20:12:17 MIL libsnapper(27668) Btrfs.cc(cmpDirs):1307 - stopwatch
31.206086s for comparing directories
2015-02-18 20:12:17 MIL libsnapper(27668) Comparison.cc(create):160 - found
10754 lines
2015-02-18 20:12:17 MIL libsnapper(27668) Comparison.cc(save):225 - num1:2650
num2:2651
2015-02-18 20:12:47 MIL libsnapper(27668) snapperd.cc(main):282 - Exiting