If a lease update raises an exception that is recoverable (such as
specifying an invalid date range) the lease would be set to ERROR
status. Other cases with wrong input have similar effects.
This change allows for non fatal exceptions to be specified in
the lease status code. If one is raised, the lease is restored
to the original status.
Closes-Bug: #1786031
Change-Id: I73df4587d223dc4582cb15e0f4cb8de1a02ffee7
d4cb8f428e