Comment 3 for bug 1858667

^ ignore this, we aren't calling locks serially in this way.

The issue I was hitting was due to both the test [1] and the periodic it was calling [2] making their own calls to target_cell against hosts in different cells. I've mocked out the second call in the periodic to workaround this.

[1] https://github.com/openstack/nova/blob/1fa6799e4171d7c93f4d6330f2437891733d7d27/nova/tests/functional/test_cross_cell_migrate.py#L988-L991 (destination host)
[2] https://review.opendev.org/#/c/699291/7/nova/compute/api.py@3715 (source host)