rgw: preserve RGWZoneGroup::master_zone on last zone deletion

the logic to clear master_zone was added recently in
https://github.com/ceph/ceph/pull/47679, but broke the multisite test
case test_zg_master_zone_delete:

  $ radosgw-admin period update --commit
  ERROR: zonegroup remove_zg should have a master zone

Fixes: https://tracker.ceph.com/issues/58127
Signed-off-by: Casey Bodley <cbodley@redhat.com>

diff --git a/src/rgw/driver/rados/rgw_zone.cc b/src/rgw/driver/rados/rgw_zone.cc
index d9e750541d7c25ee756b2be6273979519428dc92..339d337b6d440d5f4bdaf19501318c9edfbafdf4 100644 (file)
--- a/src/rgw/driver/rados/rgw_zone.cc
+++ b/src/rgw/driver/rados/rgw_zone.cc
@@ -900,8 +900,7 @@ int remove_zone_from_group(const DoutPrefixProvider* dpp,
       ldpp_dout(dpp, 0) << "NOTICE: promoted " << m->second.name
          << " as new master_zone of zonegroup " << zonegroup.name << dendl;
     } else {
-      zonegroup.master_zone.clear();
-      ldpp_dout(dpp, 0) << "NOTICE: cleared master_zone of zonegroup "
+      ldpp_dout(dpp, 0) << "NOTICE: removed master_zone of zonegroup "
           << zonegroup.name << dendl;
     }
   }