How to split a `.dup` configuration file for Backupninja into multiple files?

[dmitrii_fediuk]

As I see, Mirantis was able to preprocess .dup files with Python:

• gerrit.mcp.mirantis.com/plugins/gitiles/salt-formulas/backupninja/+/b2eb3f63/backupninja/files/dup.conf
• archive.is/4CMB7