Repro test for LiteCore 437 - Unable to push new revisions after pulling an already-conflicted doc from server

Reproduce https://github.com/couchbase/couchbase-lite-core/issues/437

This has been fixed on the Sync Gateway side by https://github.com/couchbase/sync_gateway/pull/3349, so to repro, you will need to use an older build such as the 2.0.0/815 build.  Any builds before https://github.com/couchbase/sync_gateway/pull/3349 was merged should work.