install/rpm: fix use the 'zypper addrepo' command
install/rpm: fix use the 'zypper addrepo' command

The 74034fe0348b94aedb247910f0d1c88842f4c3ac instroduced a failure:

  Warning: No repositories defined.
  Use the 'zypper addrepo' command to add one or more repositories.

The wipe command returns exit code 6 if there is no repos in the system.

Signed-off-by: Kyr Shatskyy <82d0c7561ff7e9a20a19db22e8fb5b2adaa3d71e@suse.com>

ceph/teuthology,SUSE/teuthology,ktdreyer/teuthology,dmick/teuthology,ktdreyer/teuthology,dmick/teuthology,SUSE/teuthology,ceph/teuthology,SUSE/teuthology,dmick/teuthology