Merge pull request #3363 from canonical/fix-snapshot-restore-rollback

[snapshots] Fix restore rollback

src/platform/backends/shared/base_virtual_machine.cpp

@@ -506,7 +506,6 @@ void BaseVirtualMachine::restore_rollback_helper(const Path& head_path,
  VMSpecs& specs)
 {
  // best effort only
- old_head->apply();
  specs = old_specs;
  if (old_head != head_snapshot)
  {
@@ -524,8 +523,6 @@ void BaseVirtualMachine::restore_snapshot(const std::string& name, VMSpecs& spec
  assert_vm_stopped(state); // precondition
  assert_vm_stopped(snapshot->get_state()); // precondition
 
- snapshot->apply();
-
  const auto head_path = derive_head_path(instance_dir);
  auto rollback = make_restore_rollback(head_path, specs);
 
@@ -542,6 +539,7 @@ void BaseVirtualMachine::restore_snapshot(const std::string& name, VMSpecs& spec
  persist_head_snapshot_index(head_path);
  }
 
+ snapshot->apply();
  rollback.dismiss();
 }