INFO: mock.py version 1.2.13 starting (python version = 2.7.8)...
Start: init plugins
INFO: tmpfs initialized
INFO: selinux disabled
Finish: init plugins
Start: run
INFO: Start(/var/tmp/rdiff-backup/rdiff-backup-1.2.8-12.fc21.art.src.rpm)  Config(epel-5-x86_64)
Start: clean chroot
INFO: unmounting tmpfs.
WARNING: tmpfs-plugin: exception while umounting tmpfs! (cwd: /mnt/dar/packages/rdiff-backup)
WARNING: tmpfs-plugin: exception while force umounting tmpfs! (cwd: /mnt/dar/packages/rdiff-backup)
ERROR: Exception(/var/tmp/rdiff-backup/rdiff-backup-1.2.8-12.fc21.art.src.rpm) Config(epel-5-x86_64) 0 minutes 2 seconds
INFO: Results and/or logs in: /var/lib/mock/epel-5-x86_64/result
Traceback (most recent call last):
  File "/usr/sbin/mock", line 833, in <module>
    main()
  File "/usr/lib/python2.7/site-packages/mockbuild/trace_decorator.py", line 84, in trace
    result = func(*args, **kw)
  File "/usr/sbin/mock", line 649, in main
    run_command(options, args, config_opts, commands, buildroot, state)
  File "/usr/lib/python2.7/site-packages/mockbuild/trace_decorator.py", line 84, in trace
    result = func(*args, **kw)
  File "/usr/sbin/mock", line 729, in run_command
    do_rebuild(config_opts, commands, buildroot, args)
  File "/usr/lib/python2.7/site-packages/mockbuild/trace_decorator.py", line 84, in trace
    result = func(*args, **kw)
  File "/usr/sbin/mock", line 495, in do_rebuild
    post=post_build, clean=clean)
  File "/usr/lib/python2.7/site-packages/mockbuild/trace_decorator.py", line 84, in trace
    result = func(*args, **kw)
  File "/usr/sbin/mock", line 438, in rebuild_generic
    commands.clean()
  File "/usr/lib/python2.7/site-packages/mockbuild/trace_decorator.py", line 84, in trace
    result = func(*args, **kw)
  File "/usr/lib/python2.7/site-packages/mockbuild/backend.py", line 72, in clean
    self.buildroot.delete()
  File "/usr/lib/python2.7/site-packages/mockbuild/trace_decorator.py", line 84, in trace
    result = func(*args, **kw)
  File "/usr/lib/python2.7/site-packages/mockbuild/buildroot.py", line 563, in delete
    util.rmtree(self.basedir, selinux=self.selinux)
  File "/usr/lib/python2.7/site-packages/mockbuild/trace_decorator.py", line 84, in trace
    result = func(*args, **kw)
  File "/usr/lib/python2.7/site-packages/mockbuild/util.py", line 136, in rmtree
    rmtree(fullname, selinux=selinux, exclude=exclude)
  File "/usr/lib/python2.7/site-packages/mockbuild/trace_decorator.py", line 84, in trace
    result = func(*args, **kw)
  File "/usr/lib/python2.7/site-packages/mockbuild/util.py", line 136, in rmtree
    rmtree(fullname, selinux=selinux, exclude=exclude)
  File "/usr/lib/python2.7/site-packages/mockbuild/trace_decorator.py", line 84, in trace
    result = func(*args, **kw)
  File "/usr/lib/python2.7/site-packages/mockbuild/util.py", line 136, in rmtree
    rmtree(fullname, selinux=selinux, exclude=exclude)
  File "/usr/lib/python2.7/site-packages/mockbuild/trace_decorator.py", line 84, in trace
    result = func(*args, **kw)
  File "/usr/lib/python2.7/site-packages/mockbuild/util.py", line 136, in rmtree
    rmtree(fullname, selinux=selinux, exclude=exclude)
  File "/usr/lib/python2.7/site-packages/mockbuild/trace_decorator.py", line 84, in trace
    result = func(*args, **kw)
  File "/usr/lib/python2.7/site-packages/mockbuild/util.py", line 145, in rmtree
    os.rmdir(path)
OSError: [Errno 16] Device or resource busy: '/var/lib/mock/epel-5-x86_64/root/var/cache/yum'