If user adds new disk, then virtnbdbackup could create new full backup for this disk.

**Version used**
1.9.42

**Describe the bug**
If virtnbdbackup works in incremental mode with some number of disks, and user adds another one, then backup brokes with error.

**Expected behavior**
If user adds new disk, then virtnbdbackup must create new full backup for this disk.

**Hypervisor information:**
- OS: Rocky Linux 9.2
- HV type: libvirt

**Logfiles:**
[2023-09-12 16:14:33] INFO lib common - printVersion [MainThread]: Version: 1.9.42 Arguments: /bin/virtnbdbackup --domain backup-test --level inc --compress --output /kvm/backups/0c06fc90-c706-4342-825b-29647658b840_backup-test_1
[2023-09-12 16:14:33] INFO root virtnbdbackup - main [MainThread]: Backup level: [inc]
[2023-09-12 16:14:33] INFO root virtnbdbackup - main [MainThread]: Compression enabled, level [2]
[2023-09-12 16:14:33] INFO root virtnbdbackup - main [MainThread]: Libvirt library version: [9000000]
[2023-09-12 16:14:33] INFO root virtnbdbackup - main [MainThread]: Backup will save [3] attached disks.
[2023-09-12 16:14:33] INFO root virtnbdbackup - main [MainThread]: Concurrent backup processes: [3]
[2023-09-12 16:14:33] INFO root checkpoint - redefine [MainThread]: Loading checkpoint list from: [/kvm/backups/0c06fc90-c706-4342-825b-29647658b840_backup-test_1/checkpoints]
[2023-09-12 16:14:33] INFO root checkpoint - create [MainThread]: Checkpoint handling.
[2023-09-12 16:14:33] INFO root checkpoint - create [MainThread]: Next checkpoint id: [3].
[2023-09-12 16:14:33] INFO root checkpoint - create [MainThread]: Parent checkpoint name [virtnbdbackup.2].
[2023-09-12 16:14:33] INFO root checkpoint - create [MainThread]: Using checkpoint name: [virtnbdbackup.3].
[2023-09-12 16:14:33] INFO root virtnbdbackup - main [MainThread]: Local NBD Endpoint socket: [/var/tmp/virtnbdbackup.2164493]
[2023-09-12 16:14:33] INFO root virtnbdbackup - main [MainThread]: Temporary scratch file target directory: [/var/tmp]
[2023-09-12 16:14:33] INFO root virtnbdbackup - startBackupJob [MainThread]: Starting backup job.
[2023-09-12 16:14:33] INFO fs fs - freeze [MainThread]: Freezed [1] filesystems.
[2023-09-12 16:14:33] INFO fs fs - thaw [MainThread]: Thawed [1] filesystems.
[2023-09-12 16:14:33] ERROR root virtnbdbackup - startBackupJob [MainThread]: Failed to start backup: [checkpoint inconsistent: missing or broken bitmap 'virtnbdbackup.2' for disk 'vdc']

**Workaround:**
no