bug#20616: mkdir: -p breaks -Z

[Hannes Reich]

The "-Z" (set SELinux context) option to mkdir appears to have no effect 
when "-p" (no error if existing, create parents) is also specified.

For example, on my CentOS 7 system, the correct context for 
subdirectories of "/home" is "user_home_dir_t", but when I create such a 
directory with "mkdir -p -Z", it has the "home_root_t" context:

    # rm -rf /home/with-p
    # mkdir -p -Z /home/with-p
    # ls -Zd /home/with-p
    drwxr-xr-x. root root unconfined_u:object_r:home_root_t:s0 /home/with-p
    #

That's wrong. Running restorecon(1) fixes it:

    # restorecon -v /home/with-p
    restorecon reset /home/with-p context 
unconfined_u:object_r:home_root_t:s0->unconfined_u:object_r:user_home_dir_t:s0
    #

Without the "-p" option, "-Z" works as expected:

    # mkdir -Z /home/without-p
    # ls -Zd /home/without-p
    drwxr-xr-x. root root unconfined_u:object_r:user_home_dir_t:s0 
/home/without-p
    # restorecon -v /home/without-p
    #

The coreutils version in CentOS 7 is 8.22.

coreutils-8.23 compiled from source has the same behaviour.