Handle edge case

rs/nns/governance/src/governance.rs

@@ -6988,19 +6988,30 @@ impl Governance {
                             // This is different from what we do in most places because we usually rely
                             // on trapping to retain the lock, but we can't do that here since we're not
                             // working on a single neuron.
-                            self.with_neuron_mut(&neuron_id, |neuron| {
-                                neuron.maturity_e8s_equivalent = neuron_stake;
-                                neuron.cached_neuron_stake_e8s = 0;
-                                neuron.spawn_at_timestamp_seconds =
-                                    original_spawn_at_timestamp_seconds;
-                            });
                             println!(
                                 "{}Error spawning neuron: {:?}. Ledger update failed with err: {:?}. \
-                                Reverted state, so another attempt can be made.",
+                                Reverting state, so another attempt can be made.",
                                 LOG_PREFIX,
                                 neuron_id,
                                 error,
-                                );
+                            );
+                            match self.with_neuron_mut(&neuron_id, |neuron| {
+                                neuron.maturity_e8s_equivalent = neuron_stake;
+                                neuron.cached_neuron_stake_e8s = 0;
+                                neuron.spawn_at_timestamp_seconds =
+                                    original_spawn_at_timestamp_seconds;
+                            }) {
+                                Ok() => (),
+                                Err(e) => {
+                                    println!(
+                                        "{} Error reverting state for neuron: {:?}. Retaining lock: {}"
+                                        LOG_PREFIX,
+                                        neuron_id,
+                                        e
+                                    );
+                                    lock.retain();
+                                }
+                            };
                         }
                     };
                 }