kernel.core_pattern is resetted on c/r

>Description of problem:
>[root@s139 ~]# vzctl create 201
Creating Container private area (.centos-7) with applications from config (ve-basic.conf-sample)
...
Container 201 was successfully registered
Container private area /vz/private/201 created
>[root@s139 ~]# vzctl start 201 --wait
Starting Container ...
...
Container start in progress, waiting ...
Container was started successfully
>[root@s139 ~]# vzctl exec 201 mkdir -p /vz/coredumps
>[root@s139 ~]# echo "kernel.core_pattern = |/bin/cp /dev/stdin /vz/coredumps/core-%e-%t.%p" >> /vz/root/201/etc/sysctl.conf
>[root@s139 ~]# vzctl exec 201 sysctl -e -p
kernel.core_pattern = |/bin/cp /dev/stdin /vz/coredumps/core-%e-%t.%p
>[root@s139 ~]# vzctl exec 201 sysctl kernel.core_pattern
kernel.core_pattern = |/bin/cp /dev/stdin /vz/coredumps/core-%e-%t.%p
>[root@s139 ~]# vzctl suspend 201
Setting up checkpoint...
Checkpointing finished successfully
Unmount image: /vz/private/201/root.hdd
Unmounting file system at /vz/root/201
Unmounting device /dev/ploop11205
Container is unmounted
Checkpointing completed successfully
>[root@s139 ~]# vzctl resume 201
Restoring the Container ...
Mount image: /vz/private/201/root.hdd
Opening delta /vzt/private/201/root.hdd/root.hds
Adding delta dev=/dev/ploop11205 img=/vzt/private/201/root.hdd/root.hds (rw)
Mounting /dev/ploop11205p1 at /vz/root/201 fstype=ext4 data='balloon_ino=12,pfcache_csum,,'
Container is mounted
Configure memguarantee 0%
Setting permissions for image=/vz/private/201/root.hdd
Setting permissions 104 dev 0x2bc0b651
Ok
Container was restored successfully
>[root@s139 ~]# vzctl exec 201 sysctl kernel.core_pattern
>kernel.core_pattern = core
[root@s139 ~]# cat /vz/root/201/etc/sysctl.conf
# System default settings live in /usr/lib/sysctl.d/00-system.conf.
# To override those settings, enter new settings here, or in an /etc/sysctl.d/<name>.conf file
#
# For more information, see sysctl.conf(5) and sysctl.d(5).
kernel.core_pattern = |/bin/cp /dev/stdin /vz/coredumps/core-%e-%t.%p

>How reproducible:
always

>Steps to Reproduce:
see description

>Actual results:
kernel.core_pattern = default value (core)
>Expected results:
kernel.core_pattern = value before c/r

>Host OS:
[root@s139 ~]# cat /etc/virtuozzo-release
Virtuozzo release 7.0.0 (1575)
[root@s139 ~]# uname -r
3.10.0-327.3.1.vz7.10.10
[root@s139 ~]# rpm -q criu
criu-1.8.0.12-1.vz7.x86_64