api/admin: fix volume info formatting

Newline was put in a wrong place.

Fixes QubesOS/qubes-issues#3831

qubes/api/admin.py

@@ -347,7 +347,7 @@ class QubesAdminAPI(qubes.api.AbstractQubesAPI):
         info = ''.join('{}={}\n'.format(key, _serialize(getattr(volume, key)))
             for key in volume_properties)
         try:
-            info += '\nis_outdated={}'.format(volume.is_outdated())
+            info += 'is_outdated={}\n'.format(volume.is_outdated())
         except NotImplementedError:
             pass
         return info

qubes/tests/api_admin.py

@@ -363,7 +363,7 @@ class TC_00_VMs(AdminAPITestCase):
             b'private')
         self.assertEqual(value,
             ''.join('{p}={p}-value\n'.format(p=p) for p in volume_properties) +
-            '\nis_outdated=False')
+            'is_outdated=False\n')
         self.assertEqual(self.vm.volumes.mock_calls,
             [unittest.mock.call.keys(),
              unittest.mock.call.__getattr__('__getitem__')('private'),