bp:MB-8545: do not allow node self-rename if name is set manually

Change-Id: I4492a2c3ee4822e7439b531fb39b6ba6e459a421
Orig-Reviewed-on: http://review.couchbase.org/27264
Reviewed-on: http://review.couchbase.org/27518
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>