Centos7 ct gets short hostname when /etc/hostname exists

>Description of problem:

When a Centos7 container has a /etc/hostname (which is optional) the container gets a non fqdn hostname set.

using vzctl-4.9.4-1.x86_64

>How reproducible:

>Steps to Reproduce:
1 vzctl create 2016051001 --ostemplate=centos-7-x86_64-minimal --layout simfs
3. vzctl start 2016051001
2. vzctl set 2016051001 --hostname=test.localdomain --save
3. vzctl exec 2016051001 hostname
test.localdomain
4. vzctl exec 2016051001 cat /etc/hostname
cat: /etc/hostname: No such file or directory
5. vzctl exec 2016051001 touch /etc/hostname
6. vzctl set 2016051001 --hostname=test.localdomain --save
7. vzctl exec 2016051001 hostname
test
8. vzctl exec 2016051001 cat /etc/hostname
test

>Actual results:

non fqdn "test"

>Expected results:

fqdn "test.localdomain"

>Host OS:

Centos 6

>Guest OS:

Centos 7

>Additional info (see https://openvz.org/Reporting_OpenVZ_problem):

I see online that some distributions expect a non fqdn in /etc/hostname
But this does not seem to be the case for Centos 7.

Also using de official tools in the container seem to show this;

# vzctl exec 2016051001 hostnamectl set-hostname test.localdomain

# vzctl exec 2016051001 hostname
test.localdomain

# vzctl exec 2016051001 cat /etc/hostname
test.localdomain