oe-selftest: look for expected error in stderr.
The output was moved from stdout to stderr in a recent aktualizr commit.
@@ -191,7 +191,7 @@ class ManualControlTests(OESelftestTestCase):
"""
sleep(20)
stdout, stderr, retcode = self.qemu_command('aktualizr-info')
- self.assertIn(b'Can\'t open database', stdout,
+ self.assertIn(b'Can\'t open database', stderr,
'Aktualizr should not have run yet' + stderr.decode() + stdout.decode())
stdout, stderr, retcode = self.qemu_command('aktualizr once')
