MB-10510: Handle rollback case

Rollback seqno is a tuple instead of an integer.

Change-Id: I1081dfb5362c4399b16b797d4b48c5ab5b586914
Reviewed-on: http://review.couchbase.org/34713
Tested-by: Bin Cui <bin.cui@gmail.com>
Reviewed-by: Bin Cui <bin.cui@gmail.com>