ScheduledActionService crashes on Android 8

[rivaldi8]

Steps to reproduce the behaviour

1. Schedule an action.
2. Restart the application.

Expected behaviour

Scheduled actions are run periodically.

Actual behaviour

The service crashes due to the new Android 8 restrictions on background services.

Software specifications

• GnuCash Android version: 2.3
• System Android version: 8

[rivaldi8]

Fixed in develop (94bfc01).