c/backend: added explicit check if the raft conifguration has override

Added a check in `cluster::controller_backend` validating if
configuration override has been reset before trying to finish the
update. The dependency is already there as backend is waiting for the
leader to be elected and confirmed however it is easier to read when the
dependency is explicitly expressed

Signed-off-by: Michał Maślanka <michal@redpanda.com>

src/v/cluster/controller_backend.cc

@@ -209,6 +209,15 @@ std::error_code check_configuration_update(
           partition->ntp());
         return errc::partition_configuration_in_joint_mode;
     }
+
+    if (includes_self && partition->raft()->has_configuration_override()) {
+        vlog(
+          clusterlog.trace,
+          "[{}] contains current node and there is configuration override "
+          "active",
+          partition->ntp());
+        return errc::partition_configuration_in_joint_mode;
+    }
     /*
      * if replica set is a leader it must have configuration committed i.e. it
      * was successfully replicated to majority of followers.

src/v/raft/consensus.h

@@ -524,6 +524,10 @@ class consensus {
         return _replication_monitor;
     }
 
+    bool has_configuration_override() const {
+        return _configuration_manager.has_configuration_override();
+    }
+
 private:
     friend replication_monitor;
     friend replicate_entries_stm;