upgrades: Don't ignore apt error during distribution upgrade

- This is important because only if all the command succeed, the changes to
/etc/apt/sources.list file are committed.

Tests:

- Set the time to 2025-09-20. Distribution updates are triggered. 'apt update'
fails due an mismatch with release file's timestamp. Instead of proceeding, the
distribution upgrade is halted.

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

plinth/modules/upgrades/distupgrade.py

@@ -74,8 +74,11 @@ distribution_info: dict = {
 
 def _apt_run(arguments: list[str], enable_triggers: bool = False):
     """Run an apt command and ensure that output is written to stdout."""
-    return action_utils.run_apt_command(arguments, stdout=None,
-                                        enable_triggers=enable_triggers)
+    returncode = action_utils.run_apt_command(arguments, stdout=None,
+                                              enable_triggers=enable_triggers)
+    if returncode:
+        raise RuntimeError(
+            f'Apt command failed with return code: {returncode}')
 
 
 def _sources_list_update(old_codename: str, new_codename: str):

plinth/modules/upgrades/tests/test_distupgrade.py

@@ -19,13 +19,17 @@ from plinth.modules.upgrades import distupgrade
 @patch('subprocess.run')
 def test_apt_run(run):
     """Test that running apt command logs properly."""
-    run.return_value.returncode = 10
+    run.return_value.returncode = 0
     args = ['command', 'arg1', 'arg2']
-    assert distupgrade._apt_run(args) == 10
+    distupgrade._apt_run(args)
     assert run.call_args.args == \
         (['apt-get', '--assume-yes', '--quiet=2'] + args,)
     assert not run.call_args.kwargs['stdout']
 
+    run.return_value.returncode = 10
+    with pytest.raises(RuntimeError):
+        distupgrade._apt_run(args)
+
 
 def test_sources_list_update(tmp_path):
     """Test that updating a sources file works."""