Don't exhaust view iterator until done flag is set

Otherwise we might not get all metadata, causing some tests to fail at
times

Change-Id: I67bf4dc185162d8dc985ca7184535d1c31d5188c
Reviewed-on: http://review.couchbase.org/29715
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Volker Mische <volker.mische@gmail.com>