Description of problem:
Mock rebuilt src.rpm without any problem but it was unable to clean directories in /tmp

sh$ mock --root fedora-23-x86_64 --resultdir . --rebuild ./sssd-1.13.3-5.fc24.src.rpm 

//snip
INFO: Done(./sssd-1.13.3-5.fc24.src.rpm) Config(fedora-23-x86_64) 2 minutes 23 seconds
INFO: Results and/or logs in: .
INFO: Cleaning up build root ('cleanup_on_success=True')
Start: clean chroot
Finish: clean chroot
Finish: run
WARNING: unable to delete selinux filesystems (/tmp/mock-selinux-plugin.s36m2duq): [Errno 1] Operation not permitted: '/tmp/mock-selinux-plugin.s36m2duq'

There are not any recent AVCs
[root@graviton ~]# ausearch -m avc -ts recent
<no matches>
[root@graviton ~]# ausearch -m user_avc -ts recent
<no matches>

Version-Release number of selected component (if applicable):
mock-1.2.15-1.fc24.noarch

How reproducible:
Deterministic

Steps to Reproduce:
1. just try to rebuild any package


Actual results:
Warning is printed and related file "/tmp/mock-selinux-plugin.*" is not removed.

Expected results:
There isn't any warning.

Additional info:
sh$ ls -l /tmp/mock-selinux-plugin.s36m2duq 
-r--r--r--. 1 root root 343 Mar  3 13:32 /tmp/mock-selinux-plugin.s36m2duq