Odd host lease expiring in the middle of update goes undetected

[a1exsh]

And leads to the following problem (i.e. an endless loop at the last step):

2017-05-18 13:05:25,477 INFO: Waiting for new instance to attach vol-1234abc
channel 2: open failed: connect failed: Connection refused
2017-05-18 13:05:36,497 INFO: DownEndpointCount: None
Connection to <oddhost> closed by remote host.
2017-05-18 13:05:41,564 INFO: DownEndpointCount: None
2017-05-18 13:05:46,633 INFO: DownEndpointCount: None
2017-05-18 13:05:51,704 INFO: DownEndpointCount: None
2017-05-18 13:05:56,773 INFO: DownEndpointCount: None
2017-05-18 13:06:01,847 INFO: DownEndpointCount: None
2017-05-18 13:06:06,912 INFO: DownEndpointCount: None
2017-05-18 13:06:11,982 INFO: DownEndpointCount: None
2017-05-18 13:06:17,054 INFO: DownEndpointCount: None
2017-05-18 13:06:22,296 INFO: DownEndpointCount: None
2017-05-18 13:06:27,365 INFO: DownEndpointCount: None
2017-05-18 13:06:32,434 INFO: DownEndpointCount: None
2017-05-18 13:06:37,501 INFO: DownEndpointCount: None
2017-05-18 13:06:42,569 INFO: DownEndpointCount: None
2017-05-18 13:06:47,633 INFO: DownEndpointCount: None
2017-05-18 13:06:52,701 INFO: DownEndpointCount: None
...