This is similar, but not the same as,
MDEV-12102. The latter was fixed in 10.1 but the same appears again. The issue is that the mariadb.systemd script fails when Galera is enabled. Also, in the case SELinux has to be enabled to reproduce.
The issue seems to be with the galera_recover script that fails when run from mariadb.service but runs fine from the commandline when SELinux is enabled, with SELinux disabled all runs fine. This also means that the galera_new_cluster script also does not work, as this restarts mariadb using systemd. Disabling SELinux will fix this. Also, all runs fine with Galera not configured, so SELinux has to be enabled and Galera configured for this issue to appear.