unit: default resolution check (#2463)
unit: default resolution check (#2463)

* check the default resolution logic
  * when generation is different
  * when one revision is deleted.
* equality check with the success revision also added
couchbase/couchbase-lite-ios,couchbase/couchbase-lite-ios,couchbase/couchbase-lite-ios,couchbase/couchbase-lite-ios,couchbase/couchbase-lite-ios,couchbase/couchbase-lite-ios