minetest: Handle upgrade from 5.3.0 to 5.6.1

Closes: #2134.

Tests:

1. In testing container, install Minetest and change the
configuration.

2. Manually downgrade minetest-server and minetest-data to a slightly
older version (5.5.0+dfsg+~1.9.0mt4+dfsg-1).

3. In /var/lib/dpkg/status, change the hash for
/etc/minetest/minetest.conf.

4. Run "apt update".
- minetest-server package is upgraded.
- Configuration changes are kept.

Signed-off-by: James Valleroy <jvalleroy@mailbox.org>
Reviewed-by: Sunil Mohan Adapa <sunil@medhas.org>

plinth/modules/minetest/__init__.py

@@ -11,10 +11,10 @@ from plinth.daemon import Daemon
 from plinth.modules.backups.components import BackupRestore
 from plinth.modules.firewall.components import Firewall
 from plinth.modules.users.components import UsersAndGroups
-from plinth.package import Package, Packages
-from plinth.utils import format_lazy
+from plinth.package import Package, Packages, install
+from plinth.utils import Version, format_lazy
 
-from . import manifest
+from . import manifest, privileged
 
 _mods = [
     Package('minetest-mod-3d-armor') | Package('minetest-mod-player-3d-armor'),
@@ -98,6 +98,22 @@ class MinetestApp(app_module.App):
         super().setup(old_version)
         self.enable()
 
+    def force_upgrade(self, packages):
+        """Force upgrade minetest to resolve conffile prompt."""
+        if 'minetest-server' not in packages:
+            return False
+
+        # Allow upgrade from 5.3.0 to 5.6.1
+        package = packages['minetest-server']
+        if Version(package['new_version']) > Version('5.7~'):
+            return False
+
+        config = get_configuration()
+        install(['minetest-server'], force_configuration='new')
+        privileged.configure(**config)
+
+        return True
+
 
 def load_augeas():
     """Initialize Augeas."""